Remove NPM and use git submodules

[brickpop]

• NPM is not a solidity package manager
• NPM/Yarn allow for arbitrary code execution on packages with postInstall scripts, only skipped by a flag that is trivial to forget
• Some testing scripts were using FFI (for some reason)

This PR:

• Eliminates NPM everywhere possible
  • npm-artifacts is kept for obvious reasons
• Adds just-foundry as the task+environment runner

Other:

• Avoids FFI completely
• Removing unrestricted write permission of solidity files to the project root
• Pins versions to an explicit, specific commit ID
• Removes unnecessary and convoluted multi-layer dependencies
• Removes scripts that are unusable, by design