fix(datepicker): reactive forms in onpush components

[valorkin]

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• read and followed the CONTRIBUTING.md guide.
• built and tested the changes locally.
• added/updated tests.
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• added/updated demos.

[codecov]

Codecov Report

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@@              Coverage Diff              @@
##             development   #2947   +/-   ##
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  Coverage               ?   70.7%           
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  Files                  ?     137           
  Lines                  ?    4165           
  Branches               ?     737           
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  Hits                   ?    2945           
  Misses                 ?     914           
  Partials               ?     306

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[YevheniiaMazur]

Tested, looks good