Rollup merge of #107769 - compiler-errors:pointer-like, r=eholk

Rename `PointerSized` to `PointerLike`

The old name was unnecessarily vague. This PR renames a nightly language feature that I added, so I don't think it needs any additional approval, though anyone can feel free to speak up if you dislike the rename.

It's still unsatisfying that we don't the user which of {size, alignment} is wrong, but this trait really is just a stepping stone for a more generalized mechanism to create `dyn*`, just meant for nightly testing, so I don't think it really deserves additional diagnostic machinery for now.

Fixes #107696, cc ``@RalfJung``
r? ``@eholk``