GlFilteredSearch: Add option to hide tokens dropdown on submission

Summary

Currently we show tokens list dropdown as long as cursor is in filter input textbox, and we also allow user to hit Enter/Return keys while the cursor is still in input field to submit already selected tokens, and this leads to UX where user is done with selecting filters but is still seeing tokens list dropdown. See the gif below showing what exactly happens (taken from linked discussion);

A workaround to this as of now is to manually call .blur on input field on submit event handler, but it would be better if this can be optionally configured on the component itself.