[BUGFIX] Add uploaded file to IRRE

The postMessage sent to IRRE when uploading a file via drag & drop missed
the actionName, which resulted in ignoring the message. The actionName is
now used and also streamlined to match the actual behavior.

Resolves: #90534
Releases: master
Change-Id: Ic56059762a6822e27ac64ea6fc07b5d37fc34c9a
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63434


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Tobi Kretschmann <tobi@tobishome.de>
Tested-by: Alexander Grein <alexander.grein@gmail.com>
Tested-by: Susanne Moog <look@susi.dev>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Tobi Kretschmann <tobi@tobishome.de>
Reviewed-by: Daniel Goerz <daniel.goerz@posteo.de>
Reviewed-by: Alexander Grein <alexander.grein@gmail.com>
Reviewed-by: Susanne Moog <look@susi.dev>