Enable qirlib to exist on its own

[idavis]

Closes #45. Closes #52

• All QIR functionality has been previously moved to qirlib.
• LLVM submodule is removed. LLVM is now cloned locally automatically by cmake by either:
  • git cloning and building from source code
  • pre-compiled binaries are downloaded
• Manylinux container now runs as the current user
• Manylinux now specifies Rust 1.57.0 as the build version
• The qirlib project specifies Rust 1.56 is the lowest version supported
• LLVM build download URL's must now be specified by a user (no defaults).

[kuzminrobin]

I did my best reviewing what I'm sort of close to. But have to get back to my high-priority task. Sorry.