[TASK] Detect and import xml file as well as t3d on ext initialization

Whenever installing an extension, the file located at
EXT:ext_key/Initialisation/data.t3d is detected and its content imported.
This patch adds support for EXT:ext_key/Initialisation/data.xml file as
well.

Resolves: #59154
Releases: 6.2
Change-Id: Ie5cf843ed7fff24c0cc022892d68fa86ba14a674
Reviewed-on: https://review.typo3.org/30464
Reviewed-by: Tymoteusz Motylewski
Tested-by: Tymoteusz Motylewski
Reviewed-by: Fabien Udriot
Tested-by: Fabien Udriot
Reviewed-by: Zbigniew Jacko
Tested-by: Zbigniew Jacko
Reviewed-by: Xavier Perseguers
Reviewed-by: Steffen Ritter
Tested-by: Xavier Perseguers