Consistency around SdrAngleItem in svx/sxciaitm.hxx

...similar to what has been done for svx/sdtmfitm.hxx in
68969cc61adecac481ae9656978ef952f435b310 "Consistency around SdrMetricItem."

Change-Id: I8e76e4751e50f5952c6dfff9ee10362166bf0523