[BUGFIX] Change behavior of new element during drag & drop into node

- place input correctly
- open node with children while holding the mouse over
this node for one second (when drag-adding new node)
- add chevron and expand it when adding first child
- refactor node.open to node.expand because they did the same thing
- show icons for custom doktypes (fix regex)

Releases: master
Resolves: #83306
Change-Id: I0255fa50f836d002392ed7791eed1ac3517cb400
Reviewed-on: https://review.typo3.org/55061


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>