Strip `uf` and `tf` with `strip_cache`

[jClugstor]

Checklist

• [ x] Appropriate tests were added
• [ x] Any code changes were done in a way that does not break public API
• [ x] All documentation related to code changes were updated
• [ x] The new code follows the contributor guidelines, in particular the SciML Style Guide and COLPRAC.
• [ x] Any new documentation only uses public API

Additional context

Related to solution stripping for better serialization of Solution types. Some caches include fields tf and uf that hold function information in a field f. This makes sure that if strip_solution is called on a solution with those included, it strips them away.