Rollup merge of #139541 - compiler-errors:transmute, r=lcnr

Instantiate higher-ranked transmute goal w/ placeholders before emitting sub-obligations

This avoids an ICE where we weren't keeping track of bound variables correctly in the `Freeze` obligations we emit for transmute goals. We could use `rebind` instead on that goal, but I think it's better just to instantiate the binder.

Fixes #139538

r? `@lcnr` or reassign

Author: matthiaskrgr