Adapt to https://github.com/rocq-prover/rocq/pull/21851

[proux01]

Adapt to rocq-prover/rocq#21851

This should be backward compatible and can be merged without waiting for the upstream PR.

[JasonGross]

This should be backward compatible

This is not backwards compatible with the movement of things between stdlib and corelib

File "./src/Rewriter/Util/FixCoqMistakes.v", line 2, characters 27-36:
Error: Cannot find a physical path bound to logical path
Morphisms with prefix Stdlib.

File "./src/Rewriter/Util/IffT.v", line 1, characters 28-43:
Error: Cannot find a physical path bound to logical path
RelationClasses with prefix Corelib.

[proux01]

This is backward compatible down to 9.0. Also note that rewriter is flagged as "plugin" in Rocq CI and we usually only expect those to compile on Rocq master.