Writes a custom unsigned extrinic creator due to subxt having an internal error with the scale metadata. While the code in our scope increased, it's much more ergonomic to our usage. We may end up rewriting most of subxt, eventually.
Updates to the latest serai-dex/substrate due to depending on 10ccaca0eb498a2316bbf627d419b29b1a75933a.
Also performs a general update with a variety of upgraded Substrate depends.