[TASK] Configuration: Make searchbox clearable and fix scroll position

This patches ensures the page is scrolled to the right position
upon opening a subtree.
Additionally, the "clear search" button is added to the search field.

Releases: master
Resolves: #72155
Change-Id: I4227ab0d362b8be2bb531dd341fb30e5d50d37ab
Reviewed-on: https://review.typo3.org/45202


Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Tested-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>