Introduce MemcachedValue Protocol and Conformances

[dkz2]

This issue will focus on implementing a MemcachedValue protocol to handle the conversion of generic types to ByteBuffer. We will provide conformances for standard Swift types (Int, UInt, String, etc.) to MemcachedValue. This implementation will aim to enhance our type safety by ensuring we only allow for certain types to be stored in Memcached. Additionally, we will need to update our get and set methods in the Connection Actor to make use of our new MemcachedValue protocol, along with updating our unit and integration test to ensure our connection actor and MemcachedValue works as expected.