feat: add Valkey as a native store

[ftsartek]

Description

• Adds Valkey as a native store alternative to Redis.
• Adds an optional Litestar install dependency: litestar[valkey] which installs valkey with libvalkey as an optimisation layer.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.35%. Comparing base (87f8aa0) to head (8c85612).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3892   +/-   ##
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  Coverage   98.35%   98.35%           
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  Files         345      346    +1     
  Lines       15605    15660   +55     
  Branches     1725     1730    +5     
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+ Hits        15348    15403   +55     
  Misses        122      122           
  Partials      135      135           

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[ftsartek]

I went through and basically replicated the existing Redis tests for Valkey. They're just new tests, though I'm open to a less-duplicative approach if anyone can point me in the right direction (I guess parametrise all the currently-redis-specific tests and then add checks for type to handle client._redis vs client._valkey, etc?).

The only thing that came up is that Valkey uses server.call instead of the valkey.call analogue you might expect for Redis' redis.call, but otherwise the scripts are identical.

I'm going to leave this as it is now pending any feedback.

[cofin]

LGTM. I think this is fine for the initial implementation. There is probably some larger restructuring we'll do on a few things for 3.0, and this may be part of it. However, i think it's better to get this implemented in smaller chunks.

[cofin]

@all-contributors add @ftsartek for docs, tests and code

[allcontributors]

@cofin

I've put up a pull request to add @ftsartek! 🎉

[github-actions]

Documentation preview will be available shortly at https://litestar-org.github.io/litestar-docs-preview/3892