Add 2 new rules

* no_superfluous_elseif
* no_useless_else

Both rules only apply if the if-statement contains a return. If this
is the case the obsolete else/elseif part is dropped.

Resolves: #82183
Releases: master,8.7
Change-Id: I94dfa6b5b96cbc3e350bd778f1796dda1a4d955a
Reviewed-on: https://review.typo3.org/53791


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>