Windows: Serverless command "dynamodb install" not found.

**Actual Behaviour**

`sls dynamodb install` yields:

```powershell
>sls dynamodb install
Serverless: Running "serverless" installed locally (in service node_modules)

Serverless Error ---------------------------------------

Serverless command "dynamodb install" not found. Run "serverless help" for a list of all available commands.

Get Support --------------------------------------------
Docs: docs.serverless.com
Bugs: github.com/serverless/serverless/issues
Issues: forum.serverless.com

Your Environment Information ---------------------------
Operating System: win32
Node Version: 15.8.0
Framework Version: 1.71.3
Plugin Version: 3.8.4
SDK Version: 2.3.2
Components Version: 2.30.11
```

I have installed `serverless-dynamodb-local` plugin, and `serverless help` shows it:
```powershell
>serverless help
Serverless: Running "serverless" installed locally (in service node_modules)

Commands
* You can run commands with "serverless" or the shortcut "sls"
* Pass "--verbose" to this command to get in-depth plugin info
* Pass "--no-color" to disable CLI colors
* Pass "--help" after any for contextual help

Interactive Quickstart
* Run serverless (or shortcut sls) without any arguments to initialize an interactive setup
of functionalities related to given service or current environment
* Pass "--help-interactive" for contextual help on interactive CLI options

Framework
* Documentation: http://slss.io/docs

Environment Variables
* Set SLS_DEBUG=* to see debugging logs
* Set SLS_WARNING_DISABLE=* to hide warnings from the output
* Set SLS_MAX_CONCURRENT_ARTIFACTS_UPLOADS to control the maximum S3 upload SDK requests that are sent in parallel during the deployment of the service's artifacts. The default is 3. Note: increasing this too high might, actually, downgrade the overall upload speed

config ........................ Configure Serverless
config credentials ............ Configures a new provider profile for the Serverless Framework
create ........................ Create new Serverless service
install ....................... Install a Serverless service from GitHub or a plugin from the Serverless registry
package ....................... Packages a Serverless service
deploy ........................ Deploy a Serverless service
deploy function ............... Deploy a single function from the service
deploy list ................... List deployed version of your Serverless Service
deploy list functions ......... List all the deployed functions and their versions
invoke ........................ Invoke a deployed function
invoke local .................. Invoke function locally
info .......................... Display information about the service
logs .......................... Output the logs of a deployed function
metrics ....................... Show metrics for a specific function
print ......................... Print your compiled and resolved config file
remove ........................ Remove Serverless service and all resources
rollback ...................... Rollback the Serverless service to a specific deployment
rollback function ............. Rollback the function to a specific version
slstats ....................... Enable or disable stats
plugin ........................ Plugin management for Serverless
plugin install ................ Install and add a plugin to your service
plugin uninstall .............. Uninstall and remove a plugin from your service
plugin list ................... Lists all available plugins
plugin search ................. Search for plugins
s3deploy ...................... Deploy assets to S3 bucket
requirements .................. Serverless plugin to bundle Python packages
requirements clean ............ Remove .requirements and requirements.zip
requirements install .......... install requirements manually
requirements cleanCache ....... Removes all items in the pip download/static cache (if present)
client ........................ Generate and deploy clients
client deploy ................. Deploy serverless client code
client remove ................. Removes deployed files and bucket
dynamodb ...................... undefined
dynamodb migrate .............. Creates local DynamoDB tables from the current Serverless configuration
dynamodb seed ................. Seeds local DynamoDB tables with data
dynamodb start ................ Starts local DynamoDB
dynamodb remove ............... Removes local DynamoDB
dynamodb install .............. Installs local DynamoDB
offline ....................... Simulates API Gateway to call your lambda functions offline.
offline start ................. Simulates API Gateway to call your lambda functions offline using backward compatible initialization.
login ......................... Login or sign up for Serverless
logout ........................ Logout from Serverless
generate-event ................ Generate event
test .......................... Run HTTP tests
dashboard ..................... Open the Serverless dashboard
output ........................
output get .................... Get value of dashboard deployment profile parameter
output list ................... List all dashboard deployment profile parameters
param .........................
param get ..................... Get value of dashboard service output
param list .................... List all dashboard service outputs
studio ........................ Develop a Serverless application in the cloud.

Plugins
Assets, AwsCommon, AwsCompileAlbEvents, AwsCompileAlexaSkillEvents, AwsCompileAlexaSmartHomeEvents, AwsCompileApigEvents, AwsCompileCloudFrontEvents, AwsCompileCloudWatchEventEvents, AwsCompileCloudWatchLogEvents, AwsCompileCognitoUserPoolEvents, AwsCompileEventBridgeEvents, AwsCompileFunctions, AwsCompileIoTEvents, AwsCompileLayers, AwsCompileS3Events, AwsCompileSNSEvents, AwsCompileSQSEvents, AwsCompileScheduledEvents, AwsCompileStreamEvents, AwsCompileWebsockets, AwsConfigCredentials, AwsDeploy, AwsDeployFunction, AwsDeployList, AwsInfo, AwsInvoke, AwsInvokeLocal, AwsLogs, AwsMetrics, AwsPackage, AwsProvider, AwsRemove, AwsRollback, AwsRollbackFunction, Config, Create, Deploy, Executable, HttpApiEvents, Info, Install, InteractiveCli, Invoke, Logs, Metrics, Package, Plugin, PluginInstall, PluginList, PluginSearch, PluginUninstall, Print, Remove, Rollback, ServerlessDynamodbLocal, ServerlessEnterprisePlugin, ServerlessFullstackPlugin, ServerlessOffline, ServerlessPythonRequirements, SlStats
```

**Expected Behaviour**

DynamoDB installs.

**Tried workarounds**

[Here's](https://github.com/serverless/serverless/issues/5426) a similar issue and the solution was to install local dynamodb like this:
```
serverless plugin install --name serverless-dynamodb-local
```

I tried that too, but it didn't help. I see serverless-dynamodb-local in local node_modules:


**Environment**

This is Windows 10, my path is:
```
C:\Users\eduard\AppData\Local\Programs\Python\Python38;C:\Users\eduard\AppData\Local\Programs\Python\Python38\Scripts\;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files\Amazon\AWSCLIV2\;C:\Program Files\nodejs\;C:\Users\eduard\AppData\Roaming\npm\;C:\temp\fhirsvcs\portal\node_modules\.bin;C:\temp\fhirsvcs\portal
```

And relevant part of `serverless.yml`:
```yaml
plugins:
- serverless-s3-deploy
- serverless-python-requirements
- fullstack-serverless
- serverless-dynamodb-local
- serverless-offline
```

Start by reproducing `serverless dynamodb install` on Windows with the reported `serverless.yml` plugin configuration, then inspect how the `dynamodb install` command is registered and invoked. Done means the command is recognized and successfully installs local DynamoDB, while the related migrate, seed, start, and remove commands remain available.

Written by the indexing model from the issue text.