[BUGFIX] Check isAbsPath when creating log file

As Windows uses for example "D:" as path prefix
the log file writer fails to recognize it as valid
local file path and skips creation of the log file.
To allow usage on Windows, isAbsPath is now used to
check the file path - if it is a valid absPath it
is handled in the same way as all other local files.

Resolves: #90116
Releases: master, 9.5
Change-Id: I499eb4cba4b89f8ed6a8f280e9bb8493fa3de0f9
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/62914


Tested-by: Markus Klein <markus.klein@typo3.org>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>