VE-1470: Filter UI

https://wikia-inc.atlassian.net/browse/VE-1470
I noticed the use of both ve-ui-mwTransclusionDialog and ve-ui-mwTemplateDialog as a CSS prefix, so I don't know where the difference is drawn. If you're adding this CSS class in ve.ui.MWTemplateDialog, should the prefix be ve-ui-mwTemplateDialog instead?