[TASK] Indexed Search: Hint TypoScriptFrontendController

Having a getter here helps phpstorm find usages
of TSFE more easily.

Resolves: #102915
Releases: main
Change-Id: Ie5538fc435ac8ea8f655c1206930d65faccb62c5
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/82634


Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Benni Mack <benni@typo3.org>