fix: add grid & cell role for screen ready accessibility

[ghiscoding]

• this PR replicates an old SlickGrid PR (except the focus which can cause other issues) Make SlickGrid more accessible. mleibman/SlickGrid#616
• it also adds the tabIndex: -1 on the cell which was mentioned in the issue and it seems to work the same as Ag-Grid does, with keyboard navigation so it looks ok to me
• fixes an issue on SlickGrid project, but maybe just partially, I'm not sure since I'm a newbie with these accessibility stuff and nobody wants to help much so... pushing this PR and closing the ref issue

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (454ce99) 98.6% compared to head (f30acac) 98.6%.

Files	Patch %	Lines
packages/common/src/core/slickGrid.ts	85.8%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #1337     +/-   ##
========================================
- Coverage    98.6%   98.6%   -0.0%     
========================================
  Files         198     198             
  Lines       21281   21283      +2     
  Branches     7096    7097      +1     
========================================
+ Hits        20973   20974      +1     
- Misses        308     309      +1     

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