[!!!][TASK] Remove DB-related methods from cObj

There are some methods still available in ContentObjectRenderer
for editing content as frontend users. The methods are neither used,
nor is "user_feAdmin" (frontend administration) available since ages.

The methods were actually obsolete by TYPO3 4.5, and are now removed
without substitution.

* DBgetDelete()
* DBgetUpdate()
* DBgetInsert()
* DBmayFEUserEdit()
* DBmayFEUserEditSelect()
* exec_mm_query()
* exec_mm_query_uidList()

This also means that the following TCA options have no effect anymore
throughout the TYPO3 Core:
* [ctrl][fe_cruser_id]
* [ctrl][fe_crgroup_id]
* [ctrl][fe_admin_lock]

Resolves: #75711
Releases: master
Change-Id: Id2e3876363730ab9c30a8c02430bef90adc0288c
Reviewed-on: https://review.typo3.org/47683


Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Susanne Moog <typo3@susannemoog.de>
Tested-by: Susanne Moog <typo3@susannemoog.de>