(aws-lambda-python-alpha): Bundling Options do not include PIP_TRUSTED_HOST, and do not get passed to bundling

[m3newc]

Describe the bug

Bundling arguments for a PythonLayerVersion do not work as expected. When specifying a PIP_INDEX_URL, I am unable to specify PIP_TRUSTED_HOST.
Additionally, any configured indexes are not passed to the bundling stage.

Expected Behavior

Passing PIP_TRUSTED_HOST as a build argument allows full use of a mirrored pip repository.

When passing PIP_TRUSTED_HOST and PIP_INDEX_URL as a build argument, it get's passed to the pip install of the requirements.txt file

Current Behavior

Passing PIP_TRUSTED_HOST does nothing.
When configuring PIP_INDEX_URL, it passes the pipenv install, but does not get passed to the requirements.txt install

Reproduction Steps

from aws_cdk import aws_lambda, aws_lambda_python_alpha;

import pathlib;
from cdk.shared_resources import CommandHook;

from constructs import Construct;
class IAC(Construct):
    def __init__(self, scope, construct_id):
        super().__init__(scope, construct_id);
        
        self.layer = aws_lambda_python_alpha.PythonLayerVersion(self, "Utilities",
            compatible_runtimes       = [ aws_lambda.Runtime.PYTHON_3_8 ],
            compatible_architectures  = [ aws_lambda.Architecture.X86_64 ],

            # Code
            entry = str(pathlib.Path(__file__).parent),
            bundling = aws_lambda_python_alpha.BundlingOptions(
                build_args = {"PIP_INDEX_URL": "https://our-mirror.com/simple/", "PIP_TRUSTED_HOST": "our-mirror.com",
                command_hooks = CommandHook()
            )
        );

Possible Solution

Update https://github.com/aws/aws-cdk/blob/v2.135.0/packages/%40aws-cdk/aws-lambda-python-alpha/lib/Dockerfile#L8 to include ARG PIP_TRUSTED_HOST

Possibly add in a flag in Bundling Options for passing through the build_args into the pip3 install phase. This would be intended to prevent the need to duplicate the mirror information for both the pipenv install and the requirementst.txt install; in theory both would always use the same mirror, but having a flag that defaults to true just in case.

If true, it can simply turn the build_args into export statements in the before_bundling list.

Additional Information/Context

No response

CDK CLI Version

2.118.0

Framework Version

No response

Node.js Version

16.16.0

OS

Amazon Linux 2

Language

Python

Language Version

3.7

Other information

No response