Draft: Add missing subroutines from libgridman

What is the new feature

Make libfortran-support available for libgridman.

How is it implemented

Sync modules with libgridman and add missing subroutines. See https://gitlab.dkrz.de/icon-libraries/libgridman/-/merge_requests/7

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

• Test coverage does not decrease
• Reviewed by a maintainer
• Incorporate review suggestions
• 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
• Remember to edit the commit message and select the proper changelog category (feature/bugfix/other)

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