Standardize submodule name

[Lakshay983]

Some boards use common as the name for this submodule, or they use the name of the repo. Most boards use the repo name instead of common, so we should switch to UTSVT-KiCadLibraries since it's the default when adding the submodule.

What the submodule is called depends on the person making the PCB, but we can be clearer in the instructions on how we want to do things and what things need to be named. Also, some internal directories are used in the symbols like 3D models, so the names need to be standardized.

Fixing this is gonna involve:

• Updating readme to use UTSVT-KiCadLibraries instead of common
• Ctrl-f through the repo and replacing instances of common with UTSVT-KiCadLibraries