Update to latest SUNDIALS version

[jbreue16]

We are using an outdated SUNDIALS version (3.2.1 from Oct 2018) to solve initial value problems (IVP's).
The next SUNDIALS release (4.0.0) contains breaking changes; the latest version is >= 6.6.2 (Nov 2023).
We should identify relevant differences of the latest version compared to the one currently used, such as potential performance differences, interface, added/deprecated functionality. Note that we also have a general discussion on changing the time integrator (#31)

To-do

• [ ] Identify relevant changes; starting point
• [ ] Update to latest SUNDIALS version

[lieres]

The latest versions support implicit-explicit (IMEX) multirate methods.

[sleweke-bayer]

The latest versions support implicit-explicit (IMEX) multirate methods.

Only the ARKODE module, which handles only ODEs and (AFAIK) does not support sensitivities.

[schmoelder]

See also previous work done here: #69