Feature Request: Replace git submodules with Soldeer

[timbrinded]

Git submodules adds complexity to projects and increases integration friction.

Consider creating a soldeer package so that submodules can be eschewed from the snowbridge repo, which in turn will make it a lot easier for people to integrate snowbridge into their projects too!

This repo's deps are already soldeer pkgs respectively:

• prb-math
• oz
• forge-std