Make ChatCompletionCache support component config

[victordibia]

This PR makes makes ChatCompletionCache support component config

Why are these changes needed?

Ensures we have a path to serializing ChatCompletionCache , similar to the ChatCompletion client that it wraps.

This PR does the following

• Makes CacheStore serializable first (part of this includes converting from Protocol to base class). Makes it's derivatives serializable as well (diskcache, redis)
• Makes ChatCompletionCache serializable
• Adds some tests

Related issue number

Closes #5141

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://github.com/microsoft/autogen/blob/main/CONTRIBUTING.md to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

cc @nour-bouzid

[codecov]

Codecov Report

Attention: Patch coverage is 89.33333% with 8 lines in your changes missing coverage. Please review.

Project coverage is 75.63%. Comparing base (a226966) to head (56f0d49).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...autogen_ext/models/cache/_chat_completion_cache.py	76.47%	4 Missing ⚠️
...ages/autogen-core/src/autogen_core/_cache_store.py	89.47%	2 Missing ⚠️
...s/autogen-ext/src/autogen_ext/cache_store/redis.py	92.30%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5658      +/-   ##
==========================================
+ Coverage   75.56%   75.63%   +0.07%     
==========================================
  Files         171      171              
  Lines       10483    10548      +65     
==========================================
+ Hits         7921     7978      +57     
- Misses       2562     2570       +8     

Flag	Coverage Δ
unittests	75.63% <89.33%> (+0.07%)	⬆️

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