Add `--doctest-compilation-args` option to add compilation flags to doctest compilation
Fixes#67533.
Tracking issue: https://github.com/rust-lang/rust/issues/134172
It's been something I meant to take a look at for a long time and actually completely forgot... The idea is to allow to give more control over how doctests are compiled to users. To do so, this PR adds a new `--doctest-compilation-args` option which provides extra compilation flags.
r? `@notriddle`
472bbb9f0c