Remove the Session cache from the cryptostore implementations

[poljar]

This PR is another step in the #2624 epic. It moves the Olm Session cache from each individual cryptostore implementation to the CryptoStoreWrapper.

While the wrapper shouldn't be the final destination for this cache it does help with our current multi-process support which relied on the CryptoStore::clear_caches() method. This method is now gone and no further caches should be added to the store implementations.

Review commit by commit isn't advised as the API changed and changed back when the cache was removed and re-added.

• Public API changes documented in changelogs (optional)

[codecov]

Codecov Report

Attention: Patch coverage is 98.71795% with 1 line in your changes missing coverage. Please review.

Project coverage is 84.07%. Comparing base (c83fa3a) to head (7a78443).

Files	Patch %	Lines
...atrix-sdk-crypto/src/store/crypto_store_wrapper.rs	95.23%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3799      +/-   ##
==========================================
- Coverage   84.11%   84.07%   -0.05%     
==========================================
  Files         263      263              
  Lines       27476    27475       -1     
==========================================
- Hits        23111    23099      -12     
- Misses       4365     4376      +11     

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[jmartinesp]

Having no clue about the underlying crypto logic the code makes sense to me. LGTM but maybe we want someone else's review here too.

[andybalaam]

Looks good.