fix(plugin): Row Detail column sorting was offset, fixes #949

[ghiscoding]

• fixes #949
• Row Detail extension columns were offset by 1 column (ie, clicking on 2nd column would sort 1st column), internally the RowDetail extension has to be instantiated a little bit more early within Angular-Slickgrid for it to properly sync columns and so on
• added couple more Cypress E2E tests to cover the Sorting icons to be displayed under the expected column

[codecov]

Codecov Report

Merging #950 (09cc298) into master (7be3443) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #950   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           12        12           
  Lines          981       979    -2     
  Branches       329       329           
=========================================
- Hits           981       979    -2     

Impacted Files	Coverage Δ
...angular-slickgrid/extensions/slickRowDetailView.ts	100.00% <ø> (ø)
...lickgrid/components/angular-slickgrid.component.ts	100.00% <100.00%> (ø)

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