Cleanups and enhancments to JS package search typeahead

Remove the need to press enter twice when using this typeahead box.
Submit the form on enter, regardless of whether an item is selected or
not.

Signed-off-by: Dan McGee <dan@archlinux.org>
Releng release JSON view

FS#35049.

Signed-off-by: Dan McGee <dan@archlinux.org>