Update fpm configuration

[skebinger]

Summary

This addresses issue #56 when building the library with the Fortran Package Manager. The fpm configuration file is updated to allow use of profiles and extensive features to improve build quality of library when using fpm.
Requires at least fpm in version 0.13.0!

Motivation

The current fpm configuration file does not allow optimal compiler flags and features. This may cause issues especially when compiling with ifx. Suboptimal compiler flags caused SEGFAULT when array sizes were too big.

Closes #56

Changes

-added features and profiles to fpm.toml
-compiler flags transferred based on makefile
-Readme updated to reflect new fpm capability

Important note:
I could not make fpm test to work because fpm expects tests directory to be located in top level and I did not manage to set up custom tests. This was already not working previously.

Checklist

• Tests added or updated
• All tests pass locally (ctest, run_tests.sh, or fpm test)
• Docs updated if behaviour changed
• Commit messages follow Conventional Commits
• PR title follows Conventional Commits format
• No unrelated changes mixed in

[skebinger]

I am so sorry for the repeated force pushes, I had some serious troubles correctly using my gpg key.... I apologise sincerely for that spam, I am doing this for the first time.