Implement faster bios builds

[jasoncouture]

By executing llvm-objcopy, and cargo-install in parallel, we can in theory cut bios build time to 25% of it's original build time.

Local testing has taken it from ~1m to ~22s on my Ryzen 7950x

This branch:
Finished dev [unoptimized + debuginfo] target(s) in 22.53s

Main at time of writing:
Finished dev [unoptimized + debuginfo] target(s) in 58.25s

[phil-opp]

Good idea, thanks a lot! I can confirm that this change speeds up the build. On my 5900X machine cargo build now takes ~32 seconds instead of ~58 seconds.