[TEST] add RequiresSTA attribute for Wpf tests
[TEST] add RequiresSTA attribute for Wpf tests

tells nunit-console to create an STA thread when running WPF tests.
akrisiun/xwt,steffenWi/xwt,mminns/xwt,lytico/xwt,hamekoz/xwt,directhex/xwt,residuum/xwt,TheBrainTech/xwt,iainx/xwt,antmicro/xwt,hwthomas/xwt,cra0zy/xwt,mminns/xwt,mono/xwt