Add a fab build script

[Joerg Henrichs (hiker)]

PR Summary

Closes #4

Adds a Fab-based build system that compiles all files and bundles them in a library.

Sci/Tech Reviewer:
Code Reviewer:

It's not certain if this script is useful. Casim already builds with Fab in other systems (lfric, um), but since it includes a small makefile, Yaswant Pradhan (@yaswant) decided to suggest adding a Fab script here as well.

This is a very simple script that compiles all files and creates a library. I need input from the code owners if:

1. This is actually useful
2. If there is additional scope that the script should fulfil.

Note that it already extends the makefile build system in supporting different compilers (I guess appropriate compiler settings, I could only test gnu), and even support for different sites. This needs to be added (since compilation requires UM and DrHook as far as I can tell).

It needs a new release of Fab, I will update this PR once the release is done.

Code Quality Checklist

(Some checks are automatically carried out via the CI pipeline)

• I have performed a self-review of my own code
• My code follows the project's style guidelines
• Comments have been included that aid understanding and enhance the readability of the code
• My changes generate no new warnings

Testing

No testing was done, there does not seem to be any stand-alone tests that I could use.

• [N/A] If shared files have been modified, I have run the UM and LFRic Apps rose
  stem suites
• [N/A] If any tests fail (rose-stem or CI) the reason is understood and
  acceptable (eg. kgo changes)
• [N/A] I have added tests to cover new functionality as appropriate (eg. system
  tests, unit tests, etc.)

trac.log

N/A

Security Considerations

• [N/A] I have reviewed my changes for potential security issues
• [N/A] Sensitive data is properly handled (if applicable)
• [N/A] Authentication and authorisation are properly implemented (if applicable)

Performance Impact

• [N/A] Performance of the code has been considered and, if applicable, suitable performance measurements have been conducted

AI Assistance and Attribution

No AI was used.

Documentation

• Where appropriate I have updated documentation related to this change and confirmed that it builds correctly

Sci/Tech Review

• I understand this area of code and the changes being added
• The proposed changes correspond to the pull request description
• Documentation is sufficient (do documentation papers need updating)
• Sufficient testing has been completed

Please alert the code reviewer via a tag when you have approved the SR

Code Review

• All dependencies have been resolved
• Related Issues have been properly linked and addressed
• CLA compliance has been confirmed
• Code quality standards have been met
• Tests are adequate and have passed
• Documentation is complete and accurate
• Security considerations have been addressed
• Performance impact is acceptable

[Joerg Henrichs (hiker)]

Converted to draft till the next Fab release is done.