NbAutocompleteDirective : input to disable focus on input on value change

[jornetsimon]

Issue type

I'm submitting a ... (check one with "x")

• bug report
• feature request

Issue description

Current behavior:
When a value is set to the input bound to an Autocomplete, and handled by writeValue(), the input is focused.

Expected behavior:
A new NbAutocompleteDirective boolean input to manage this behaviour.

Steps to reproduce:

Related code:
autocomplete.directive.ts

@Input() focusOnInputOnValueChange: boolean;
...
handleInputValueUpdate() {
 if (this.focusOnInputOnValueChange) {
  this.hostRef.nativeElement.focus();
 }
}

[katebatura]

Closing as duplicate of #2401