aws-cdk: Build a deployable artifact

### Describe the feature

As a developer I would like the ability to generate a deployable artifact with CDK so that I can "build once and deploy many" times.

### Use Case

A mature CI/CD process can involve steps like (there are many variations, including feature flagging and canary deploys, but I will keep this simple/traditional):

**Continuous Integration phase**
1. Run unit tests, stubbed integration tests, and static code analysis
2. Build the code and IaC into a versioned deployable artifact
3. Upload this artifact to some repository
**Continuous Deployment Phase**
1. Deploy the versioned artifact from the CI step to a dev "environment" (preferably a dev AWS account)
2. Run some automated integration tests and perhaps relativistic performance tests etc.
3. Either manually or automatically promote/deploy this versioned artifact to a "test" or "uat" environment
4. Run more extensive automated and/or manual and/or exploratory tests
5. Either manually or automatically deploy the versioned artifact to a "prod" environment

Without a deployable artifact we essentially need to package up most of the repository or just pull down a specific SHA or tag. Doing this and running a deploy step that includes building the artifact again has the potential to introduce variability, thus makes promoting to further environments more risky.

### Proposed Solution

A `cdk build` capability that results in a self-contained deployable artifact that can be versioned and published to an artifact repository then later deployed while providing dynamic parameters to the deployment.

Perhaps `cdk deploy` can recognize the existence of an already built template/artifact and skip to the cloudformation deploy step.

### Other Information

AWS SAM essentially has this, by doing the following:

1. Run `sam build`
2. Package/zip up `.aws-sam/` along with a `samconfig.toml`. (** Note that the Functions can reference bundled code using the CodeUri property, without having it in account-specific S3 buckets)
4. Unpacking these and running `sam deploy --config-env ` will deploy the template and Lambda code

The `samconfig.toml` gives the ability to use environment-specific parameters, including some that come from environment-specific AWS accounts (like SSM parameters, secrets, etc.). These could include details like VPC Subnets and Security Groups for Lambdas.

### Acknowledgements

- [ ] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

### CDK version used

2.51.1 (build 3d30cdb)

### Environment details (OS name and version, etc.)

Various

Start with the cdk build and cdk deploy entry points and compare the AWS SAM build/package/deploy workflow described in the issue. Define the artifact contents, versioning, and environment-specific parameters before implementation; done means a built artifact can be deployed repeatedly without rebuilding.

Written by the indexing model from the issue text.