Enabled implicit output for generic bindings

[hallvictoria]

Description

Enables implicit output for generic types. This addresses an ask from the Logic Apps team for generic type bindings to have implicit return.

In implementing this, two main errors occurred:

1. Durable functions started failing with "FunctionLoadError: cannot load the DurableFunctionsHttpStart1 function: Python return annotation "HttpResponse" does not match binding type "durableClient""

• Cause: durableClient is a generic type and implicit output should be False
• Fix: durableClient has its own converter class in the python sdk, so it is no longer a generic type. We h;ave a special case for this type in the worker to maintain backwards compatibility

2. get_eventhub_batch_triggered failed with "TypeError: unable to encode outgoing TypedData: unsupported type "<class 'azure_functions_worker.bindings.generic.GenericBinding'>" for Python type "HttpResponse""

• Cause: functions now can have both explicit and implicit output set to true. Previously, we set the function's return type to be the type of the binding that either is called $return or has implicit output set to true. In the case where there's a generic binding (implicit output = true) and $return in the same function, return type gets overwritten, and it depends on the order in which the bindings are processed to see what the final return type is set to.
• Fix: prioritize the return type associated with $return, if that is present.
  • Case 1: $return processed before generic type
    -The boolean will be set to true and prevent the return type from later being overwritten
  • Case 2: generic type processed before $return
    -The $return return type will overwrite the implicit output binding return type
  • Case 3: no $return
    -The return type will be set to that of the implicit output binding

Fixes #

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[codecov]

Codecov Report

Attention: Patch coverage is 93.33333% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 85.61%. Comparing base (2e91fa1) to head (466ee73).

Files	Patch %	Lines
azure_functions_worker/bindings/meta.py	66.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #1391      +/-   ##
==========================================
+ Coverage   85.19%   85.61%   +0.42%     
==========================================
  Files          35       35              
  Lines        1965     1974       +9     
  Branches      370      374       +4     
==========================================
+ Hits         1674     1690      +16     
+ Misses        217      213       -4     
+ Partials       74       71       -3     

Flag	Coverage Δ
unittests	85.56% <93.33%> (+0.42%)	⬆️

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[YunchuWang]

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[nytian]

Thanks for the PR!