Sundials Update

[ajnonaka]

Summary

Changes to the time integrator interface to now support explicit, implicit, and ImEx methods with fixed or adaptive time step size, as well as MRI approaches.

Additional background

Can be tested with amrex-tutorials PR https://github.com/AMReX-Codes/amrex-tutorials/pull/123

Checklist

The proposed changes:

• [ ] fix a bug or incorrect behavior in AMReX
• [x] add new capabilities to AMReX
• [ ] changes answers in the test suite to more than roundoff level
• [ ] are likely to significantly affect the results of downstream AMReX users
• [ ] include documentation in the code and/or rst files, if appropriate