feat: Complete forum channel implementation

[Dorukyum]

Summary

Closes #1635.

Information

• This PR fixes an issue.
• This PR adds something new (e.g. new method or parameters).
• This PR is a breaking change (e.g. methods or parameters removed/renamed).
• This PR is not a code change (e.g. documentation, README, typehinting, examples, ...).

Checklist

• I have searched the open pull requests for duplicates.
• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes.
• If type: ignore comments were used, a comment is also left explaining why.

[Dorukyum]

I've added the applied_tags field to create_thread and available_tags attribute to _TextChannel as a list of integers since there's no ForumTag class as of now. Thread.edit must be completed and a ForumTag class should probably be created.
CC @BobDotCom

[Lulalaby]

ping pong conflicts and needs works
high prio

[codecov]

Codecov Report

Merging #1636 (70a9814) into master (8660f67) will increase coverage by 0.06%.
The diff coverage is 42.53%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1636      +/-   ##
==========================================
+ Coverage   33.15%   33.21%   +0.06%     
==========================================
  Files          96       96              
  Lines       18536    18653     +117     
==========================================
+ Hits         6145     6196      +51     
- Misses      12391    12457      +66     

Flag	Coverage Δ
macos-latest-3.10	33.20% <42.53%> (+0.06%)	⬆️
macos-latest-3.11	33.20% <42.53%> (+0.06%)	⬆️
macos-latest-3.8	33.21% <42.53%> (+0.06%)	⬆️
macos-latest-3.9	33.21% <42.53%> (+0.06%)	⬆️
ubuntu-latest-3.10	33.20% <42.53%> (+0.06%)	⬆️
ubuntu-latest-3.11	33.20% <42.53%> (+0.06%)	⬆️
ubuntu-latest-3.8	33.21% <42.53%> (+0.06%)	⬆️
ubuntu-latest-3.9	33.21% <42.53%> (+0.06%)	⬆️
windows-latest-3.10	33.20% <42.53%> (+0.06%)	⬆️
windows-latest-3.11	33.20% <42.53%> (+0.06%)	⬆️
windows-latest-3.8	33.21% <42.53%> (+0.06%)	⬆️
windows-latest-3.9	33.21% <42.53%> (+0.06%)	⬆️

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Impacted Files	Coverage Δ
discord/abc.py	22.33% <0.00%> (-0.50%)	⬇️
discord/http.py	22.98% <0.00%> (-0.06%)	⬇️
discord/threads.py	30.18% <21.42%> (-0.45%)	⬇️
discord/partial_emoji.py	40.40% <22.22%> (-0.65%)	⬇️
discord/channel.py	34.66% <34.84%> (-0.18%)	⬇️
discord/enums.py	78.71% <80.00%> (+0.01%)	⬆️
discord/flags.py	75.92% <100.00%> (+0.17%)	⬆️
discord/types/channel.py	100.00% <100.00%> (ø)
discord/types/threads.py	100.00% <100.00%> (ø)

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