Don't update ngModel or value of input after selection through preventDefault inside typeahead

[ruimendes29]

Is your feature request related to a problem? Please describe.

It is related to https://github.com/valor-software/ngx-bootstrap/issues/2243, as currently still some the question of that thread are not answered. I would like to have a solution to prevent the default behavior of onSelect, and prevent that the value of the control gets set on selection of an option.

Describe the solution you'd like

Either have a preventDefault on an event from onSelect that would prevent the control from changing value or have a possibility to pass from the outside method selectMatch, so I can override the whole logic.