[TASK] Streamline FAL metadata properties

In an attempt to better organize metadata properties of assets
in TYPO3, this patch reorganizes the existing fields according
to standards in editing softwares.

- Alternative Text is meant for accessibility and should be
  a single line of text
- Caption and download name are accessibility fields and are
  better grouped with Alternative Text in a dedicated palette
- Creator Tool, Publisher, Source and Copyright do not belong
  to a combined palette and should be standard separate fields
- Keywords are stored as text and the user interface should
  reflect the possibility to enter more than one line of content

Resolves: #70941
Releases: master
Change-Id: I2a80940dc40ae6b79c3c5ada86cbc02df5cbda74
Reviewed-on: https://review.typo3.org/44214


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Stephan Großberndt <stephan@grossberndt.de>
Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>