Rollup merge of #89288 - rusticstuff:lld_wrapper, r=Mark-Simulacrum

Wrapper for `-Z gcc-ld=lld` to invoke rust-lld with the correct flavor

This PR adds an `lld-wrapper` tool which is installed as `ld` and `ld64` in `lib\rustlib\<host_target>\bin\gcc-ld` directory and whose sole purpose is to invoke `rust-lld` in the parent directory with the correct flavor. Lld decides which flavor to use from either the first two commandline arguments or from the name of the executable (`ld` for GNU/ld flavor, `ld64` for Darwin/Macos/ld64 flavor and so on). Symbolic links could not be used as they are not supported by rustup and on Windows.

The wrapper replaces full copies of rust-lld which added some significant bloat. On UNIXish operating systems it exec rust-lld, on Windows it spawns it as a child process.

Fixes #88869.

r? ```@Mark-Simulacrum```
cc ```@nagisa``` ```@petrochenkov``` ```@1000teslas```

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