Change independent variable of ODEs with array variables

[hersle]

@aml5600 I found your Slack question. I also need it to work with array variables 😅
I think this should work. Thanks for writing the test!

Note that I don't use the @mtkmodel macro in the test.
I'm not completely sure how it works with the NoValue() stuff.
I'm sure there is a way to get that to work, too, which might be unrelated to change_independent_variable (?)

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

[aml5600]

@hersle yeah, I would imagine the NoValue stuff is orthogonal to the transformation. Unfortunately I used @mtkmodel heavily while learning MTK and still have it used quite a lot =/

This is a good step forward though, thank you!

[hersle]

This is ready now @ChrisRackauckas.
Would be nice to get this in together with #3625.