Expose correlation details from host

[yojagad]

Correlation details from host needs to be exposed as part of python function. This is already happening for node, java and powershell.

Bigger epic workitem: Azure/azure-functions-host#3747
Related PR: #554

[maiqbal11]

Before we can do this, we need to import the new protobuf into Python.

[Hazhzeng]

Check with Yogesh for the unit tests and check in the code.

[Hazhzeng]

#545 merged in

[KimLClark]

Kim Clark, from Alaska Airlines here, we've been waiting on this fix for python since September 2019. Did it actually get implemented? This issue points back to #545 which seems to say the PR for that code was cancelled due to test failures. Is it actually implemented in a released version? If not is it still planned to be?

[anirudhgarg]

@KimLClark yes this is done and deployed. Please let us know if its not working for you.