Fix unexpected exception in Google Calendar OAuth exchange

[allenporter]

Proposed change

Rewrite google calendar oauth exchange callbacks. The goal is to prevent this error:

2022-06-14 17:04:39 INFO (SyncWorker_10) [oauth2client.client] Successfully retrieved access token
2022-06-14 17:04:39 ERROR (MainThread) [homeassistant] Error doing job: Task exception was never retrieved
Traceback (most recent call last):
File "/usr/src/homeassistant/homeassistant/components/google/api.py", line 123, in _poll_attempt
self._exchange_task_unsub()
TypeError: 'NoneType' object is not callable

I am not totally positive how it gets into this state, but it seemed worth trying to simplify anyway. The asserts have been replaced with explicit checks before running the unsub calls.

This replaces the asserts with some other rewrite of the logic to match more common patterns seen in other code in home assistant. Instead of having a single callback for updates and a timeout, the timeout is split into a separate listener. The new code is more lines of code, but seems like it could be a bit more straight forward avoiding passing callback parameters around.

The tests that use freezetime needed to be reverted because of spulec/freezegun#89 -- not sure if that was exposed because of moving patches around or specific callbacks around.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes Google Calendars - can't get authentication #73484
• This PR is related to issue:
• Link to documentation pull request:

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