[TASK] Adjust Comments to describe string comparison

The IfViewHelper received the ability to compare strings natively some
time ago, but the comment in the class describing the usage was not
updated.

Resolves: #47034
Releases: 6.1
Change-Id: I7a41ab555908ee84dbebabc8f9147d8f61a47b2e
Reviewed-on: https://review.typo3.org/19738
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters