OMNI: Fix dimension range-indexing in frontend

[mlange05]

Just testing for now ...

This change adds a frontend sanitisation step to remove the forced lower bounds on array declaration dimensions in OMNI. This is done via a custom sanitisation Transformer.

As a result, we can remove a lot of the special-casing for OMNI's array dimension notation and, importantly, remove the use of the normalize_range_indexing utility across the loki.transformation sub-package tests. Consequently, we can also remove the OMNI special-casing in loki_transform.py - the problem that triggered this entire endeavour.

Please note, the normalize_range_indexing tool has not been removed, as it has a legitimate use in another sanitisation utility, which is part of the C-transpilation toolchain. However, all OMNI-specific workarounds using this utility have been removed.

[github-actions]

Documentation for this branch can be viewed at https://sites.ecmwf.int/docs/loki/363/index.html

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.40%. Comparing base (9a76c21) to head (29a4869).
Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #363      +/-   ##
==========================================
- Coverage   95.41%   95.40%   -0.02%     
==========================================
  Files         177      178       +1     
  Lines       37332    37267      -65     
==========================================
- Hits        35622    35555      -67     
- Misses       1710     1712       +2     

Flag	Coverage Δ
lint_rules	96.39% <ø> (ø)
loki	95.38% <100.00%> (-0.02%)	⬇️

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[reuterbal]

Many thanks, I absolutely love it!

[reuterbal]

Note that v.shape is only an indirection to v.type.shape:

loki/loki/expression/symbols.py

Lines 746 to 750 in 9a76c21

	def shape(self):
	"""
	Original allocated shape of the variable as a tuple of dimensions.
	"""
	return self.type.shape

Since you've already looked up the type, you might as well use _type.shape here and in the line below, to avoid hitting the symbol table again

[mlange05]

Good spot! Pushed a fix.