[TASK] Use t3skin-icons for DomainObject-editor

Space in the heading of that box is limited.
Replace words like "Cancel" with an icon.
Use icons from t3skin.

Change-Id: Ied2aa3148864d9a617943c19ffe20f0457b64ce3
Resolves: #57432
Reviewed-on: https://review.typo3.org/28960
Reviewed-by: Nico de Haen
Tested-by: Nico de Haen