fix(plugin): do not show drag group sort when column is not sortable

[ghiscoding]

• recent feature to add sort icon in SlickDraggableGrouping did not look at the possibility that the column itself might not be sortable, however it has to be considered

for example, below we can see that the "Market" column is not sortable and should not have the sort icon in the preheader group

[codecov]

Codecov Report

Merging #819 (d546357) into master (80c6508) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #819   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          239       239           
  Lines        16365     16366    +1     
  Branches      5547      5547           
=========================================
+ Hits         16365     16366    +1     

Impacted Files	Coverage Δ
packages/common/src/editors/editors.index.ts	100.00% <ø> (ø)
...es/common/src/extensions/slickDraggableGrouping.ts	100.00% <100.00%> (ø)

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