simplify the boostrap hashes a bit
build with bundled llvm:
the rust project has forked the llvm compiler to solve some
issues.
With pkgs.llvm the test suite fails.
See https://github.com/rust-lang/rust/pull/43026
And PR #30088
Also updates beta, nightly, nightlyBin, and bootstrap compilers.
Also updates the registry.
Also consolidates logic between bootstrap and nightlyBin compilers.
Also contains some miscellaneous cleanups.
Also patches firefox to build with the newer cargo