Implement register and unregister on wallet API, add tests

[Riven-Spell]

I felt like the wallet API was a bit lacking in it's ability to manage assets (and this does somewhat hinder testing on the Go SDK), so I added the ability to register and deregister assets via the RPC.

Some use cases this could be good for:

• A user is developing a dApp with an associated CA, and they need to deploy their CA alongside their test as they may be using a self-hosted chain (kinda like I do in the Go SDK)
• A user is intending to delist the CA, and has a script to deregister the CA as soon as all assets have been reclaimed