Resolve "Revisit find_package commands in CMake scripts"

What is the bug

A package-NOTFOUND is undetected and does not raised a problem. See #20 (closed) This MR closes #20 (closed)

How do you fix it

The OpenMP find package is made REQUIRED.
The find package for OpenACC has to stay QUIET or else it will try to look for both OpenACC_C and OpenACC_Fortran. (LUMI does not have OpenACC_C at the moment.)

How urgent is the bugfix

• I need it as soon as possible
• I can wait for a couple of days
• None of my current codes is directly affected

Mandatory steps before review

• Gitlab CI passes (Hint: use make format for linting)
• Bugfix 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 What is the bug and How do you fix it 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!