[TASK] Change PHP namespace of EXT:jumpurl to FoT3

Change the PHP namespace and the according
composer.json information to FoT3 in preparation
of removing the extension from the Core.

Resolves: #71083
Releases: master
Change-Id: Ifd1018f36f6c7114c3f32ef293097e0c0cac1156
Reviewed-on: https://review.typo3.org/44323


Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>