More documentation with samples in typescript

There's this [walkthrough](https://docs.aws.amazon.com/cloudformation-cli/latest/userguide/resource-type-walkthrough.html) but it's using *java* as the language, and it's not very easy to understand.

From the documentation perspective, I don't understand how to call `dynamodb` from the handlers for example. It looks like I need to use the `SessionProxy`, but it's not documented how to get a hold of *dynamodb* aws client.
In the *init* example:
```
// Example:
try {
if (session instanceof SessionProxy) {
const client = session.client('S3');
}
```
1. Where's the documentation of which *string* should I pass in the `.client([string])` to get dynamodb, stepfunction (or others) clients?

2. Even after I run `npm install` to install the dependencies, VSCode still does not find `@amazon-web-services-cloudformation/cloudformation-cli-typescript-lib`


3. Also, do I need to implement all "create, update, list, read..." operations? I was looking for to implement only *create*, *update* and *delete*.

Review the linked AWS CloudFormation resource-type walkthrough and the TypeScript init example using SessionProxy. Verify how service clients such as DynamoDB are named and obtained, why the installed TypeScript library is not found by VSCode, and which handlers are required; done means the walkthrough answers these questions with working samples.

Written by the indexing model from the issue text.