[BUGFIX] Skip dynamically assigned instance names in extension scanner

Dynamically created class instances using a variable name cannot be
resolved in extension scanner - given the fact that a class member
variable can change at any time and the scanner would have to keep
that state - which is too much for static code analysis.

Thus, the following source code is not analyzed.

$className = SomeClass::class;
$object = GeneralUtility($className);

Resolves: #91128
Releases: master, 9.5
Change-Id: I7f87e7c88e9e62efb85ee54f32625c531266cbba
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64251


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Christian Eßl <indy.essl@gmail.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Ghanshyam Bhava <ghanshyambhava@yahoo.com>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Christian Eßl <indy.essl@gmail.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Ghanshyam Bhava <ghanshyambhava@yahoo.com>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>