Properly handle compiler versions

[hiker]

Atm compiler versions are only handled as strings. We need to properly convert them to integer-tuples to allow comparison, and also support compiler-specific compiler flags to be added

[jasonjunweilyu]

This is the current way of how LFRic makefiles do compiler version comparison. I have converted this into Python:

compiler_version_comparison = ''.join(f"{int(version_component):02d}" for version_component in compiler.get_version().split('.')) 

if compiler_version_comparison >= '190000':
    runtime_flags = ...
else: ...

So current get_version() returns a string 1.20.0. It is converted to string 012000 and then compared with string 190000