Changed FakeQuantumRunStream to support arbitrary response and exception timing

[verult]

The previous version of FakeQuantumRunStream has the limitation that a response or exception is only fired when it receives a request. This makes it impossible to test these scenarios:

• Raising an exception before receiving a request or after sending a response
• Respond to a request which is not the most recently received one.

This version supports both cases:

• Tests can call reply() to send a response or raise an exception at any moment.
• Tests can set the response message_id to one from a different request.

With this functionality, it would be possible to write a test for sending requests after breaking a stream, which would have revealed a bug discovered through manual testing.

@maffoo @wcourtney

[verult]

The latest commit addressed several issues:

• Bypasses typecheck errors in faking QuantumEngineServiceAsyncClient
• Fixed "task got bad yield" errors due to asyncio.Queue() being initialized in the duet thread.
• Introduced the ability to wait for multiple requests to be sent in FakeQuantumRunStream.wait_for_requests(). Otherwise, test_submit_twice_and_break_stream_expect_result_responses might flake because only one of the two expected GetQuantumResultRequests may have been sent after the ServiceUnavailable exception.

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.01% ⚠️

Comparison is base (6fae409) 97.88% compared to head (2ef0730) 97.88%.

❗ Current head 2ef0730 differs from pull request most recent head db9552a. Consider uploading reports for the commit db9552a to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6253      +/-   ##
==========================================
- Coverage   97.88%   97.88%   -0.01%     
==========================================
  Files        1104     1106       +2     
  Lines       95692    95778      +86     
==========================================
+ Hits        93667    93751      +84     
- Misses       2025     2027       +2     

Files Changed	Coverage Δ
...q-google/cirq_google/engine/stream_manager_test.py	100.00% <100.00%> (ø)

... and 39 files with indirect coverage changes

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