[mod] Update input when selecting by TAB

When the user press [TAB] the input form should be filled with the highlighted
item from the autocomplete list, but not release a search / with other words:
what we now have by pressing once on [ENTER] should be mapped to the [TAB] key
and pressing [ENTER] once should release a search query. [1]

[1] https://github.com/searxng/searxng/issues/778#issuecomment-1016593816



Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>