(closes #3135) Fix cyclic dependencies by replacing Scalartype import-time instantiations

[sergisiso]

I hit #3135 again where some cyclic dependencies cannot be prevented by adding the import inside methods because they happen when symbols are initialised at import-time. To remove this import time instantiations I opted for creating ScalarType staticmethods instead of the factory proposed in the issue. The change itself is small, but it is repeated many many times.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.96%. Comparing base (b45ff81) to head (13e794c).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3436   +/-   ##
=======================================
  Coverage   99.96%   99.96%           
=======================================
  Files         391      391           
  Lines       54668    54692   +24     
=======================================
+ Hits        54649    54673   +24     
  Misses         19       19           

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[sergisiso]

@LonelyCat124 @arporter This is ready for review

[LonelyCat124]

@sergisiso I struggled to look through every single change (my browser is dying looking at the diffs...) but I found some minor issues to check with imports in examples and docs - can you check these? Then I can probably merge.

[sergisiso]

@LonelyCat124 This is ready for another review.

[LonelyCat124]

Set ITs running as a sanity check but otherwise all is good.

[sergisiso]

@LonelyCat124 the integration test spotted a INTEGER_TYPE in lfric_apps. I will push a fix now