* Add the response type for `z_validateaddress`
* Add UAs to the address variants
* Remove a redundant TODO
* Impl `z_validateaddress`
* Add basic test vectors
* Add basic snapshots
* Remove a deprecated field from the RPC response
* Add basic snapshot data
* Check the semantic validity of UAs
* Refactor imports
* Refactor snapshot filenames
This PR removes the `.new` filename extensions from snapshots.
* Rename `address` to `unified_address`