Fix typeahead directive for AoT

[isaacplmann]

The HostListeners need to be public if compiling with AoT and the events are being bound to some other function in the app code as well.

This PR fixes this scenario when AoT compiling:

<input [typeahead]="list" (focus)="someFunction($event)" (blur)="someFunction($event)">

[codecov-io]

Current coverage is 89.60% (diff: 100%)

Merging #1083 into development will not change coverage

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  Files               26         26          
  Lines              789        789          
  Methods            143        143          
  Messages             0          0          
  Branches           116        116          
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  Hits               707        707          
  Misses              82         82          
  Partials             0          0          

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[Martin-Luft]

#1086 was merged -> close this PR

[valorkin]

@isaacplmann thanks for your help!