[BUGFIX] Use moment.unix for visualizing regular unix timestamps

A dialog trying to prevent overriding existing files in the filelist
module shows an incorrect modification date of files that are existing
on the server-side. When using regular unix timestamps (instead of
micro-timestamps), dedicated `moment.unix` function has to be used.

Resolves: #97724
Releases: main, 11.5, 10.4
Change-Id: Ieb5a00aaf87410e9721e39d91b9e0da13a109bc6
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/74816


Tested-by: core-ci <typo3@b13.com>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>