(dialects): improving stencil attr syntax mlir compatibility

[n-io]

MLIR interoperability needs the (generic) format changed from #stencil.index[0] to #stencil.index<[0]>, and likewise for #stencil.bounds where it also doesn't like the colon.

A practical implication of this is that the syntax of stencil.store has changed, for instance, from
stencil.store %5 to %3 ([0, 0, 0] : [64, 64, 64]) to
stencil.store %5 to %3 (<[0, 0, 0], [64, 64, 64]>)

This PR does not modify the syntax of any ops, and only modified the printing and parsing of the index and bounds attributes. In a future PR, the syntax of the store op (maybe also others) could be reviewed.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.90%. Comparing base (2d67e7c) to head (d1ec704).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2947   +/-   ##
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  Coverage   89.90%   89.90%           
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  Files         407      407           
  Lines       50864    50878   +14     
  Branches     7873     7873           
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+ Hits        45729    45743   +14     
  Misses       3894     3894           
  Partials     1241     1241           

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[PapyChacal]

Thanks!!