Add default logging handler to web.run_app (#3243)

[0az]

Fixes #3243.

What do these changes do?

Add a default logging handler to web.run_app.

Are there changes in behavior for the user?

If the Application.debug flag is set and the default logger aiohttp.access is used, access logs will now be output using a stderr StreamHandler if no handlers are attached. Furthermore, if the default logger has no log level set, the log level will be set to DEBUG.

Related issue number

This issue fixes #3243.

Checklist

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes
• If you provide code modification, please add yourself to CONTRIBUTORS.txt
  • The format is <Name> <Surname>.
  • Please keep alphabetical order, the file is sorted by names.
• Add a new news fragment into the CHANGES folder
  • name it <issue_id>.<type> for example (588.bugfix)
  • if you don't have an issue_id change it to the pr id after creating the pr
  • ensure type is one of the following:
    • .feature: Signifying a new feature.
    • .bugfix: Signifying a bug fix.
    • .doc: Signifying a documentation improvement.
    • .removal: Signifying a deprecation or removal of public API.
    • .misc: A ticket has been closed, but it is not of interest to users.
  • Make sure to use full sentences with correct case and punctuation, for example: "Fix issue with non-ascii contents in doctest text files."

[codecov-io]

Codecov Report

Merging #3324 into master will decrease coverage by 0.01%.
The diff coverage is 80%.

@@            Coverage Diff            @@
##           master   #3324      +/-   ##
=========================================
- Coverage   98.01%     98%   -0.02%     
=========================================
  Files          43      43              
  Lines        8025    8030       +5     
  Branches     1356    1359       +3     
=========================================
+ Hits         7866    7870       +4     
  Misses         66      66              
- Partials       93      94       +1

Impacted Files	Coverage Δ
aiohttp/web.py	97.8% <80%> (-1.04%)	⬇️

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[webknjaz]

@0az could you please come up with some sort of a regression test?

[0az]

Not sure what's going on with codecov.

In any case, now that there's a set of tests, I think this can be merged.

[asvetlov]

@0az thanks!

[lock]

This thread has been automatically locked since there has not been
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related bugs.

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please include those exceprts into that new issue.