aws_cdk.aws_lambda_python_alpha:: Install extra packages in BundlingOptions

### Describe the feature

Is it possible to add an option to pass extra packages to the [default Dockerfile](https://github.com/aws/aws-cdk/blob/v2.72.0/packages/%40aws-cdk/aws-lambda-python/lib/Dockerfile) used for bundling the lambda layer zip file?

### Use Case

I have several packages in my CodeArtifact private PyPI repo that use C++ extensions, so when pip tries to install them, it would throw an error saying that it requires `cmake` to be present inside the Docker container. I know I could just copy the default Dockerfile and add `yum install -y cmake`, but I'd like to know if there can be a better way.

### Proposed Solution

_No response_

### Other Information

_No response_

### Acknowledgements

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

### CDK version used

2.70.0

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

Windows 11 22H2

Start with packages/@aws-cdk/aws-lambda-python/lib/Dockerfile and the BundlingOptions API for the Python Lambda module. Trace how the default Dockerfile is selected during layer bundling and review existing bundling tests. Done means users have a supported way to provide extra packages such as cmake, with the behavior covered by tests.

Written by the indexing model from the issue text.