Add a unit test for AbstractTypolinkBuilder::resolveTargetAttribute.

Releases: master, 8.7
Resolves: #80618
Change-Id: I429900c036371be4f0bd57e75d841f9d0dfe7720
Reviewed-on: https://review.typo3.org/52305


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>