(towards #2577) Add support for pointer assignments

[sergisiso]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.85%. Comparing base (4d10caa) to head (09d4cec).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2583      +/-   ##
==========================================
- Coverage   99.86%   99.85%   -0.01%     
==========================================
  Files         351      352       +1     
  Lines       48396    48455      +59     
==========================================
+ Hits        48331    48386      +55     
- Misses         65       69       +4     

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[sergisiso]

This is ready for a first look from @arporter or @hiker . It adds support for pointer assignments (removes the CodeBlocks), but not symbol attributes (does not remove UnknownFortranType for its symbols). It also adds support in the frontend for Fortran2003.Data_Pointer_Object fparser object. For now I added some broad protections in the base loop_trans and region_trans to prevent transformation to apply to code that have pointer assignments (which can be disabled with a transformation option).

[sergisiso]

@arporter This is ready for next review. In comparison to the first review I found out that pointer expressions that have array accessor ranges in the inner element are not described like regular arrays in the standard/fparser. So I decided to not support these cases yet - they are CodeBlocks as before.

[arporter]

Almost there. A few small things to tidy and there's a conflict with mlc_config because it has been removed on master.
Ref. guide still builds fine.
I'll launch the integration tests.

[sergisiso]

@arporter This is ready for another review

[arporter]

(Virtually) all requested changes have been made. I'll take the liberty of fixing the remaining typo.
I've checked the Dev and User Guides and they don't require updating.
Integration tests were all green.
Will proceed to merge.