[!!!][TASK] Remove deprecated TSFE properties and methods

Removed public properties:
* TypoScriptFrontendController->intTarget
* TypoScriptFrontendController->extTarget
* TypoScriptFrontendController->fileTarget
* TypoScriptFrontendController->spamProtectEmailAddresses
* TypoScriptFrontendController->baseUrl
* TypoScriptFrontendController->xhtmlDoctype
* TypoScriptFrontendController->xhtmlVersion

Changed visibility from public to protected:
* TypoScriptFrontendController->type

Removed public methods:
* TypoScriptFrontendController->initUserGroups()
* TypoScriptFrontendController->isUserOrGroupSet()
* TypoScriptFrontendController->isBackendUserLoggedIn()
* TypoScriptFrontendController->checkEnableFields()
* TypoScriptFrontendController->baseUrlWrap()
* TypoScriptFrontendController->doWorkspacePreview()
* TypoScriptFrontendController->whichWorkspace()

Resolves: #100994
Related: #100963
Related: #99416
Related: #97866
Related: #100405
Related: #96996
Related: #97531
Related: #99170
Releases: main
Change-Id: I4ce4f5a57648e7ec22e88ab9bff1dfac294d1dca
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/79256


Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Thomas Hohn <tho@gyldendal.dk>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>