feat(thunder_xymatic): add default and paragraph_preview entity view …

[chrfritsch]

…displays for media.xymatic bundle

feat(thunder_xymatic): add media.xymatic.thumbnail view display configuration file

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[IT-Cru]

LGTM

I think at some point default view mode should be switched to Xymatic Player field formatter, when this is ready in Xymatic contrib module on d.o

Config for Thunder 7 could be maybe have different requirements for new Gin admin theme layouts.