Refactor `clarity` to enable lightweight serialization crate

[Jiloc]

The clarity crate currently includes the full Clarity VM, which brings in many heavy dependencies (rusqlite, etc.). This makes it difficult for downstream crates that only need to serialize or deserialize Clarity Value types, as they are forced to compile the entire VM.

This issue tracks the work to refactor the clarity crate to isolate its core serialization/deserialization functionality from the virtual machine.