[TASK] Make SVG category tree use JS Icon API

This change make SVG tree expect icon identifier instead of icon source
in JSON node data.
Tree fetches icon source via JS Icon API only once per icon type.
This makes JSON response few times smaller.

Resolves: #82849
Releases: master
Change-Id: I8954837f68cee3bcc316bc56e30788e0d16c81d6
Reviewed-on: https://review.typo3.org/54468


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>