Add missing Awaitable return types

[natehardison]

SSHServer.*_requested() callbacks can return Awaitables of their respective Session types, or a tuple consisting of a channel and a Session awaitable.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.83%. Comparing base (fab96ac) to head (9ba054f).
Report is 126 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #749      +/-   ##
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- Coverage    99.85%   99.83%   -0.02%     
===========================================
  Files           95      100       +5     
  Lines        27784    31386    +3602     
  Branches      2908     3026     +118     
===========================================
+ Hits         27743    31335    +3592     
- Misses          38       45       +7     
- Partials         3        6       +3     

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[ronf]

Thanks for submitting this!

You're right that all of the places you identified can accept a coroutine. However, I have a helper type called MaybeAwait that I generally use for signaling this. It wraps around a return type and automatically adds both the plain return type and an Awaitable of that type, cutting down on some of the duplication which would otherwise have been required here.

See commit 266a25f for the MaybeAwait version of this change. It should be the equivalent of what you suggested. If you find any problem with it, please let me know!