fix(plugins): do not recreate header button plugin after re-render

[ghiscoding]

• there is no need to recreate the header button because if we do that then we lose previous ref and onCommand stops working

[codecov]

Codecov Report

Merging #706 (58c6a7d) into master (7219249) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #706   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          159       159           
  Lines        10611     10615    +4     
  Branches      3754      3755    +1     
=========================================
+ Hits         10611     10615    +4     

Impacted Files	Coverage Δ
...es/angular-slickgrid/services/extension.service.ts	100.00% <ø> (ø)
...dules/angular-slickgrid/services/filter.service.ts	100.00% <ø> (ø)
...slickgrid/filter-conditions/dateFilterCondition.ts	100.00% <100.00%> (ø)
...ickgrid/filter-conditions/numberFilterCondition.ts	100.00% <100.00%> (ø)

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