1815: Support correct `$crate` expansion in macros r=uHOOCCOOHu a=uHOOCCOOHu
This PR makes normal use cases of `$crate` from macros work as expected.
It makes more macros from `std` work. Type inference works well with `panic`, `unimplemented`, `format`, and maybe more.
Sadly that `vec![1, 2, 3]` still not works, but it is not longer an issue about macro.
Screenshot:
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Co-authored-by: uHOOCCOOHu <hooccooh1896@gmail.com>