[FEATURE] Add begin/maxItems options to FILES ContentObject

The FILES ContentObject always renders all files. If you access
the media field of a page you probably only want to render the
first attached file. This patch adds begin and maxItems as properties
to TypoScript.

Releases: 6.2
Resolves: #52632
Documentation: #52742
Change-Id: I9755571d5a1a692fbd4b5ea2b3ef82cc99fa2cc1
Reviewed-on: https://review.typo3.org/24558
Reviewed-by: Stefan Neufeind
Tested-by: Stefan Neufeind
Reviewed-by: Francois Suter
Tested-by: Francois Suter