[fix][fn] Forward source message properties in Python runtime

[sbourkeostk]

Fixes #17773

Motivation

The Python functions runtime currently ignores the forward-source-message-property option and does not forward message properties. This PR fixes that.

Modifications

python_instance.py has been modified to check for the flag and copy the message properties if requested. Tests have been added.

Verifying this change

• Make sure that the change passes the CI checks.

This change added tests and can be verified by running the Python functions tests.

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• Dependencies (add or upgrade a dependency)
• The public API
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• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
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• Anything that affects deployment