Make QSvgCssProperties' ctor explicit


It's expensive and should not be used accidentally.

Pick-to: 6.12
Change-Id: Ib038cd44c05fc0c354c507bd1d88cb10d94a30eb
Reviewed-by: Hatem ElKharashy <hatem.elkharashy@qt.io>
commit2cba6002dca3781bd9fe4de085c8df8673d4ecb8
parent099e4c54fafe9284563491abe147f6223017ef05
authorRobert Löhning <robert.loehning@qt.io>
committerRobert Löhning <robert.loehning@qt.io>
commit timeFri, 25 Sep 2026 13:43:47 +0000