1721: Impl/dyn trait r=flodiebold a=flodiebold
This adds support for `impl Trait` and `dyn Trait` types as far as possible without Chalk. So we can represent them in the type system, and handle them in method resolution, but Chalk doesn't know about them yet. There's a small temporary hack here where we bypass Chalk during method resolution, so we can handle simple method calls on them and completion works.
Fixes#1608.
1723: Make sysroot use `RUST_SRC_PATH` if set r=matklad a=bkchr
Co-authored-by: Florian Diebold <flodiebold@gmail.com>
Co-authored-by: Bastian Köcher <git@kchr.de>