As an editors I want to easily access not just Items but also Lexemes, Properties and Entity Schemas in the search box in order to have access to all content on Wikidata.
**Problem:**
Right now the top-right search box gives and easy type-ahead search for Items. It does not work for Lexemes, Properties and Entity Schemas. For that people need to use "P:", "L:" and "E:" in front of their search terms and then get redirected to Special:Search upon pressing enter. This is not a good experience and research has shown that people are not able to figure out how to search for Lexemes for example.
**Screenshots/mockups:**
Some inspiration from Phabricator:
{F35624046}
**BDD**
GIVEN
AND
WHEN
AND
THEN
AND
**Acceptance criteria:**
*
**Open questions:**
* What about other namespaces? Help and Project namespace might also be relevant here.
**Notes:**
* See also: {T190454}
* https://www.wikidata.org/wiki/MediaWiki:Gadget-SearchAll exists and looks like this:
{F35624025}