Add supported_max_cas_entry_size property to CacheCapabilities

[amishra-u]

Context: bazelbuild/bazel#18449 (comment)

Request:
Consider adding the supported_max_cas_entry_size property to the CacheCapabilities.

Rationale:
By including this property, Bazel will be able to retrieve the max_cas_entry_size supported by the remote cache during the initial handshake. Bazel can use this information to make informed decisions about which build outputs can be uploaded to the remote cache.

[diegohavenstein]

@amishra-u if I work on bazelbuild/bazel#18449, I may grab this one as well

[diegohavenstein]

@coeuvre can you assign this one to me as well pls?