(Close #1815) Prevent OMPTargetDirectives with Codeblocks

[sergisiso]

I implemented the validation in both: the transformation and the node global validation. I have not tackled the ACCKernelDirective constraints, see https://github.com/stfc/PSyclone/issues/1815#issuecomment-1199430014 but happy to add it if needed.

[codecov[bot]]

Codecov Report

Base: 99.51% // Head: 99.51% // Increases project coverage by +0.00% :tada:

Coverage data is based on head (1c725ae) compared to base (e864331). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1819   +/-   ##
=======================================
  Coverage   99.51%   99.51%           
=======================================
  Files         263      264    +1     
  Lines       39203    39214   +11     
=======================================
+ Hits        39011    39022   +11     
  Misses        192      192           

Impacted Files	Coverage Δ
src/psyclone/psyir/transformations/region_trans.py	100.00% <ø> (ø)
src/psyclone/transformations.py	99.29% <ø> (-0.01%)	:arrow_down:
src/psyclone/psyir/nodes/omp_directives.py	99.77% <100.00%> (+<0.01%)	:arrow_up:
src/psyclone/psyir/transformations/__init__.py	100.00% <100.00%> (ø)
...psyclone/psyir/transformations/omp_target_trans.py	100.00% <100.00%> (ø)

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[sergisiso]

@arporter This is ready for review. It is a relatively small PR to close #1815 . I could also use the PR to move the OMPTargetTrans to src/psyclone/psyir/transformations if you want (the tests were already in this path), but I have not moved it for the first review to make the changes clear.

[sergisiso]

@arporter I reduced the scope of this PR to just remove codeblocks (original issue) and move the transformation locations.

The UBOUND and LBOUND issues are a compiler bug that only happens under specific conditions, so I will deal with it on the optimization script.

This is ready for another review.

[sergisiso]

@arporter This is ready for next review