Search emojis only by shortcut ':' and short name

Searching emojis was cumbersome and the toggling search field moved the whole emoji picker.
The search is now opened by simply entering ':' and the emoji's short name.
The search is removed from the normal emoji picker view.

That way, this power user feature can be accessed quicker.
For average users it makes the normal view simpler.
3 jobs for refactor/emoji-picker-search in 2 minutes and 40 seconds (queued for 198 minutes and 28 seconds)
Status Job ID Name Coverage
  Test
passed #74801
build

00:01:04

passed #74799
clazy

00:01:13

passed #74800
qmllint

00:00:22