Rollup merge of #123464 - fmease:rn-has-proj-to-has-aliases, r=compiler-errors

Cleanup: Rename `HAS_PROJECTIONS` to `HAS_ALIASES` etc.

The name of the bitflag `HAS_PROJECTIONS` and of its corresponding method `has_projections` is quite historical dating back to a time when projections were the only kind of alias type.

I think it's time to update it to clear up any potential confusion for newcomers and to reduce unnecessary friction during contributor onboarding.

r? types

Author: jhpratt