Support for single precision wp

What is the new feature

Support for single-precision as working-precision in libiconmath. Related to fortran-support (libfortran-support!98 (merged))

Related to icon-mpim milestone (https://gitlab.dkrz.de/icon/icon-mpim/-/milestones/14#tab-issues)

How is it implemented

• Precision handling: Dependent on fortran-support src/mo_iconlib_kind.f90
• Extensions of some functions to include sp and dp interfaces (independent of wp/sp).
• Related branches before libiconmath merger:
  • libmath-interpolation/feature-single-precision (https://gitlab.dkrz.de/icon-libraries/libmath-interpolation/-/tree/feature-single-precision?ref_type=heads)
  • libmath-support/feature-single-precision (https://gitlab.dkrz.de/icon-libraries/libmath-support/-/tree/feature-single-precision?ref_type=heads)

Mandatory steps before review

• Gitlab CI passes (Hint: use make format for linting)
• New feature is covered by additional unit tests
• Mark the merge request as ready by removing Draft:

Mandatory steps before merge

• Reviewed by a maintainer
• Incorporate review suggestions
• Remember to edit the commit message and select the proper changelog category (feature/bugfix/other)
• Prior to merging, please remove any boilerplate from the MR description, retaining only the Please describe your feature in a couple of words and describe important implementation details of the feature section to maintain

You are not supposed to merge this request by yourself, the maintainers of libiconmath take care of this action!