Add changed & css classes to control, group & array

[NiklasPor]

Resolves #20

• Every FormControlState now supports the initialValue property. It is set automatically when creating with one of the provided initializer functions.
• Every FormControlSummary now additional supports the changed property. It is set to true when initialValue and value are different. For object comparison again fast-equals was used.
  • CSS class .ng-changed is now set on inputs when changed: true.
  • CSS class .ng-initial is now set on inputs when changed: false.
• FormGroupSummary and FormGroupArray also support the changed property. It is set when atleast one control was changed.

[codecov[bot]]

Codecov Report

Merging #22 into master will increase coverage by 0.02%. The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #22      +/-   ##
==========================================
+ Coverage    98.3%   98.33%   +0.02%     
==========================================
  Files          20       20              
  Lines         236      240       +4     
  Branches       29       29              
==========================================
+ Hits          232      236       +4     
  Misses          3        3              
  Partials        1        1

Impacted Files	Coverage Δ
projects/ngrx-clean-forms/src/lib/init.ts	100% <ø> (ø)	:arrow_up:
.../directives/controls/abstract-control.directive.ts	100% <100%> (ø)	:arrow_up:
projects/ngrx-clean-forms/src/lib/selectors.ts	100% <100%> (ø)	:arrow_up:

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