[TASK] Add tests for GeneralUtility::implodeAttributes

This change renames some variables within
GeneralUtility::implodeAttributes and adds some first
tests to this method.

Resolves: #98597
Releases: main, 11.5
Change-Id: I5a667904e7788c76514c4832c197f37b74921bc1
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76064


Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>