Store cookies with the same name if they have different paths

[jsagarribay]

What do these changes do?

Do not overwrite cookies when they have different paths, even if they have the same name and domain

Are there changes in behavior for the user?

Without this change, if the server sets the same cookie (for example JSESSIONID) in several paths the cookie will be overwritten after each request and the session will get lost.

With this change aiohttp will do the same as browsers and store both cookies.

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 #3627 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master   #3627      +/-   ##
=========================================
+ Coverage    97.9%   97.9%   +<.01%     
=========================================
  Files          43      43              
  Lines        8556    8557       +1     
  Branches     1376    1376              
=========================================
+ Hits         8377    8378       +1     
  Misses         74      74              
  Partials      105     105

Impacted Files	Coverage Δ
aiohttp/cookiejar.py	100% <100%> (ø)	⬆️

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[PhotonQuantum]

@asvetlov @webknjaz It seems that this PR has been open for quite a long time. The issue solved by this PR prevents aiohttp from behaving correctly on a significant number of sites using tomcat, which sends JSESSIONID cookie in different paths under the same domain. Any reviews on it?

[Dreamsorcerer]

Sorry this didn't get reviewed earlier. Has been superseded by #6638.