Fix SSLContext creation in the TCPConnector with multiple loops

[bdraco]

Creation of the SSLContexts did not account for multiple event loops in different threads.

Creation is now done at import time to ensure it does not block the event loop.

fixes #9020

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.29%. Comparing base (e8d8e28) to head (bd44036).
Report is 1065 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9029      +/-   ##
==========================================
- Coverage   98.30%   98.29%   -0.01%     
==========================================
  Files         107      107              
  Lines       34355    34349       -6     
  Branches     4066     4071       +5     
==========================================
- Hits        33771    33765       -6     
  Misses        412      412              
  Partials      172      172              

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[bdraco]

Probably easier to fix the issue and include a test then try to suppress all the asyncio errors that pytest really wants to raise

[Dreamsorcerer]

I'm not overly convinced we need to support multiple loops, but you didn't change the import_time test, so it can't be that slow to do this on import.

[bdraco]

Need to check the missing coverage

[patchback]

Backport to 3.10: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 466448c on top of patchback/backports/3.10/466448c9412081e1928e08b8a3e413ef4faa1093/pr-9029

Backporting merged PR #9029 into master

1. Ensure you have a local repo clone of your fork. Unless you cloned it
   from the upstream, this would be your origin remote.
2. Make sure you have an upstream repo added as a remote too. In these
   instructions you'll refer to it by the name upstream. If you don't
   have it, here's how you can add it:

   $ git remote add upstream https://github.com/aio-libs/aiohttp.git

3. Ensure you have the latest copy of upstream and prepare a branch
   that will hold the backported code:

   $ git fetch upstream
   $ git checkout -b patchback/backports/3.10/466448c9412081e1928e08b8a3e413ef4faa1093/pr-9029 upstream/3.10

4. Now, cherry-pick PR Fix SSLContext creation in the TCPConnector with multiple loops #9029 contents into that branch:

   $ git cherry-pick -x 466448c9412081e1928e08b8a3e413ef4faa1093

   If it'll yell at you with something like fatal: Commit 466448c9412081e1928e08b8a3e413ef4faa1093 is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 466448c9412081e1928e08b8a3e413ef4faa1093

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Fix SSLContext creation in the TCPConnector with multiple loops #9029 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.10/466448c9412081e1928e08b8a3e413ef4faa1093/pr-9029

7. Create a PR, ensure that the CI is green. If it's not — update it so that
   the tests and any other checks pass. This is it!
   Now relax and wait for the maintainers to process your pull request
   when they have some cycles to do reviews. Don't worry — they'll tell you if
   any improvements are necessary when the time comes!

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[patchback]

Backport to 3.11: 💔 cherry-picking failed — conflicts found

❌ Failed to cleanly apply 466448c on top of patchback/backports/3.11/466448c9412081e1928e08b8a3e413ef4faa1093/pr-9029

Backporting merged PR #9029 into master

1. Ensure you have a local repo clone of your fork. Unless you cloned it
   from the upstream, this would be your origin remote.
2. Make sure you have an upstream repo added as a remote too. In these
   instructions you'll refer to it by the name upstream. If you don't
   have it, here's how you can add it:

   $ git remote add upstream https://github.com/aio-libs/aiohttp.git

3. Ensure you have the latest copy of upstream and prepare a branch
   that will hold the backported code:

   $ git fetch upstream
   $ git checkout -b patchback/backports/3.11/466448c9412081e1928e08b8a3e413ef4faa1093/pr-9029 upstream/3.11

4. Now, cherry-pick PR Fix SSLContext creation in the TCPConnector with multiple loops #9029 contents into that branch:

   $ git cherry-pick -x 466448c9412081e1928e08b8a3e413ef4faa1093

   If it'll yell at you with something like fatal: Commit 466448c9412081e1928e08b8a3e413ef4faa1093 is a merge but no -m option was given., add -m 1 as follows instead:

   $ git cherry-pick -m1 -x 466448c9412081e1928e08b8a3e413ef4faa1093

5. At this point, you'll probably encounter some merge conflicts. You must
   resolve them in to preserve the patch from PR Fix SSLContext creation in the TCPConnector with multiple loops #9029 as close to the
   original as possible.
6. Push this branch to your fork on GitHub:

   $ git push origin patchback/backports/3.11/466448c9412081e1928e08b8a3e413ef4faa1093/pr-9029

7. Create a PR, ensure that the CI is green. If it's not — update it so that
   the tests and any other checks pass. This is it!
   Now relax and wait for the maintainers to process your pull request
   when they have some cycles to do reviews. Don't worry — they'll tell you if
   any improvements are necessary when the time comes!

🤖 @patchback
I'm built with octomachinery and
my source is open — https://github.com/sanitizers/patchback-github-app.

[bdraco]

I'm not sure why I added skip on this one. I should have done a changelog message

[bdraco]

I'll do another PR to add it #9044