(aws-codecommit): Repository code initialization fails when empty files exist within the contents

### What is the problem?

When attempting to initialize a CodeCommit repository with some `code` contents the stack fails with a `Code supplied is not a valid .zip archive` error if, among the contents, one or more empty files exist (eg. \_\_init\_\_.py).

This behavior applies to any of the supported [Code](https://docs.aws.amazon.com/cdk/api/v2/python/aws_cdk.aws_codecommit/Code.html) sources : `from_asset`, `from_directory`, `from_zip_file`.

### Reproduction Steps

```python
# Example with from_asset
dirname = os.path.dirname(__file__)
repository_code = Asset(
scope=self,
id="RepositoryCodeAsset",
exclude=[".vscode", "__pycache__"],
path=os.path.join(dirname, "code"),
)

aws_codecommit.Repository(
scope=self,
id="CodeCommitRepository",
repository_name="repository_name",
code=aws_codecommit.Code.from_asset(asset=repository_code),
)
```

The `code` folder shall contain one or more empty files.

### What did you expect to happen?

The stack should have been deployed successfully, the code commit repository `"repository_name"` should have been created and initiated with the contents from the `code` folder.

Also, the error message could have been more precise : the zip archive is perfectly valid, the issue (assuming there is one) is with its contents.

### What actually happened?

`cdk deploy` fails with a `Code supplied is not a valid .zip archive` error on the CodeCommit resource.

### CDK CLI Version

2.8.0 (build 8a5eb49)

### Framework Version

aws-cdk-lib==2.8.0

### Node.js Version

v16.10.0

### OS

MacOS 11.6.3

### Language

Python

### Language Version

Python(3.9.10)

### Other information

_No response_

Start by reproducing the failure with the Code.from_asset, Code.from_directory, and Code.from_zip_file entry points using a directory containing an empty file. Then trace the CodeCommit repository initialization path and its handling of the generated archive. Done means deployment succeeds with empty files present and any remaining validation error accurately describes the problem.

Written by the indexing model from the issue text.