Add strip_solution

[jClugstor]

Checklist

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

Additional context

I know error(...) is discouraged, but I couldn't find one that fit, and wasn't sure if I should make one.

This also doesn't completely strip solutions made from implicit methods, since the caches still need to be dealt with.

[ChrisRackauckas]

Setup downstream tests

[thomvet]

@jClugstor : Just randomly reviewing this. It seems strange to me that the interp variable isn't used afterwards? Should it go into line 618? Otherwise, what's the point of defining it at all? Also, maybe check that the interpolation is stripped as well in the tests if this is the intended behavior here :)

[ChrisRackauckas]

Yes that looks like a typo.

[jClugstor]

Yeah, it's a typo, thanks for pointing it out .

[ChrisRackauckas]

@jClugstor what's the next steps for this?

[jClugstor]

This will need to check if the solution was made using an implicit method that has caches, if it was I'll need to strip the cache. Should I make a trait for SciMLAlgs e.g. 'has_cache' ?