DataNodeExtractTrans implementation

[LonelyCat124]

Initial implementation - transformation is quite straightforward so should be good for a review assuming CI is ok.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.95%. Comparing base (2a1efa4) to head (d386496).
⚠️ Report is 26 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3301   +/-   ##
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  Coverage   99.95%   99.95%           
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  Files         381      382    +1     
  Lines       54015    54107   +92     
=======================================
+ Hits        53993    54085   +92     
  Misses         22       22           

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[LonelyCat124]

@sergisiso @arporter This is ready for a first review. The implementation is currently pretty small and neat - if you want more functionality testing let me know and I can add more.

[arporter]

Thanks very much Aidan - as you say it's pleasingly simple. Also as you say, it could do with some more checks and associated tests :-)

On the naming front, I worry that the use of Extract will be confused with the existing ExtractTrans which is obviously quite different. IAAI (two of them) and it seems that IntroduceLocal/TemporaryTrans is a good alternative that doesn't involve "Extract".

Finally, (once everything else is done) I think it would be exciting (and possibly educational) to try this for real. I'm thinking we'd alter nemo/scripts/utils.py::normalise_loops so that it e.g. looks for any Calls which have array expressions as arguments.

[LonelyCat124]

@arporter I think I fixed all the issues I found from the last review, ready for another look.

[arporter]

Looking good @LonelyCat124 - I like your solution for the imported symbols.
I think it would be worth doing the renaming of the transformation now. Please could you also add it to the User Guide.
I've addded a real-life NEMO example to #1958 - please could you use that as the basis for an additional test?

[LonelyCat124]

@arporter Also moved to use allocatables and allocate the array as required so ready for a review now.

[arporter]

Thanks Aidan. Just small things to tidy now. I've submitted the ITs again too.

[LonelyCat124]

@arporter Fixed up the remaining issues, hopefully ready for a final look.

[arporter]

All looks good now, thanks very much Aidan. I've fired off the ITs one last (hopefully) time...

[arporter]

ITs were all fine. Ready to go.