[BUGFIX] Make headerThumbnail in IRRE records configurable

This patch allows the configuration of the thumbnail image in IRRE
record headers. It is possible to configure e.g. height and width
using the TCA configuration in "headerThumbnail".

Resolves: #42837
Releases: 6.0

Change-Id: I284e9d04676fb3d4031eac6d2f8548761e167e69
Reviewed-on: http://review.typo3.org/16377
Reviewed-by: Oliver Hader
Tested-by: Oliver Hader