Invalidate route cache when module identity changes after HMR (#16776)

The route cache stores getStaticPaths() return values keyed by route path,
but never checked whether the module that produced those values had been
re-evaluated. After HMR, components passed as props via getStaticPaths()
remained stale even on manual refresh.

Store the module reference in the cache entry and compare identity on
lookup. A new module object (from a fresh import after HMR) causes the
cache to miss, re-calling getStaticPaths() with updated references.

Fixes #16522