Cosmos Driver: Validate and Fix Go/ Rust EPK Test Gaps

[kundadebdatta]

• The goal is to test that not only is the murmurhash implementation correct, but our encoding is correct as well. We should use the Rust SDKs full PartitionKey -> EPK pipeline, and not just reimplement Go's encoding here. Go's encoding logic SHOULD be the same as Rust's, and Python's, and .NET's, and Java's. That's the intent of this test.

  let pk = PartitionKey::from(...);
  let epk = EffectivePartitionKey::compute(pk);
  assert_eq!(baseline_value, epk.as_str())
  

• Add Integration tests for pk_range_cache. It would be good if the cache is filled proactively when creating container client It would also help for removing many of the dead code snippets for this iteration.