Add bunCompileToBytecode option for mkDerivation

[gytic]

Motivation

I often use top-level awaits inside my application code.
When I want to package these applications with bun2nix
I then have to remove the --bytecode flag (see why).

For this to work I then have to re-implement the correct module path and output path options
which is a bit anoying.

Solution

Add an option for bun2nix.mkDerivation which toggles whether to use the --bytecode flag with the build command.

Other options

It might also be usefull to expose the entry point and expected out path via environment variables
so they can be consumed by custom flags set via bunBuildFlags.
However I choose the "simpler" derivation toggle because from my experience that is the only flag I oten need to control
and the rest stays as-is.

[baileylu121]

Thanks very much for this, I hope it comes in handy, I'm generally quite happy with this, I just want to enable the nix-community CI for external repos before I merge it.

[baileylu121]

lib.optional already returns a list, you can use lib.optionals instead.

This statement should really look something like this, seems like it was my mistake using it in the other case:

bunBuildFlags =
  if (args ? bunBuildFlags) then
    args.bunBuildFlags
  else
    lib.optionals (module != null) ([
      "${module}"
      "--outfile"
      "${pname}"
      "--compile"
      "--minify"
      "--sourcemap"
    ]
    ++ lib.optional bunCompileToBytecode "--bytecode"
    );