fix(theme): change @HostListener accessor modifier

[rjlopezdev]

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• I read and followed the CONTRIBUTING.md guide.
• I read and followed the New Feature Checklist guide.

Short description of what this resolves:

New nb-autocomplete component causes a build compilation error on production mode (AOT) cause of NbAutocompleteDirectivedoesn't expose @HostListener's & is used from outside class.

Code below

<input
  [formControl]="inputFormControl"
  nbInput
  type="text"
  placeholder="Form control"
  [nbAutocomplete]="autoControl" />

 <nb-autocomplete #autoControl>

  <nb-option *ngFor="let option of filteredControlOptions$ | async" [value]="option">
    {{ option }}
  </nb-option>

</nb-autocomplete>

causes the following errors:

ERROR in ...: Directive NbAutocompleteDirective, Property 'handleInput' is protected and only accessible within class 'NbAutocompleteDirective<T>' and its subclasses.
...: Directive NbAutocompleteDirective, Property 'handleKeydown' is protected and only accessible within class 'NbAutocompleteDirective<T>' and its subclasses.
...: Directive NbAutocompleteDirective, Property 'handleKeydown' is protected and only accessible within class 'NbAutocompleteDirective<T>' and its subclasses.
...: Directive NbAutocompleteDirective, Property 'handleBlur' is protected and only accessible within class 'NbAutocompleteDirective<T>' and its subclasses.

[codecov]

Codecov Report

Merging #2240 into master will decrease coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2240      +/-   ##
==========================================
- Coverage   84.45%   84.41%   -0.04%     
==========================================
  Files         248      248              
  Lines        8605     8605              
  Branches      772      772              
==========================================
- Hits         7267     7264       -3     
- Misses       1111     1114       +3     
  Partials      227      227              

Impacted Files	Coverage Δ
.../framework/theme/components/menu/menu.component.ts	77.86% <0.00%> (-1.64%)	⬇️
...rc/framework/theme/components/menu/menu.service.ts	87.32% <0.00%> (-0.71%)	⬇️

[yggg]

@rjlopezdev Thanks! I picked your changes in the #2273, so closing this one