[TASK] Convert class ApplicationType to enum

Converting the class to an enum is possible since
 * the constructor is private,
 * property $type is not exposed,
 * public functions are kept.

Resolves: #100172
Releases: main
Change-Id: I2ce736fd93f64a288300cfd7f09c5a63d18552b7
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78129


Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Benni Mack <benni@typo3.org>