Enable Rust proc macro support

[lnicola]

loadOutDirsFromCheck is now called runBuildScripts and has been enabled by default for 10 months. And proc macros are enabled in upstream by default, so maybe there's no particular reason to disable them?

2021-12-24.11-55-57.mp4

[archseer]

@luctius added these in #460, I assumed it's to avoid arbitrary code execution (an exploited crate could contain a malicious proc_macro).

Might be better to match upstream defaults though.

[lnicola]

I considered that, but executing build scripts and running cargo check on save already bring the same risks and they are enabled at the moment.

[archseer]

Agreed 👍