Fix modal support for vue apps

Signed-off-by: Joas Schilling <coding@schilljs.com>

core/src/jquery/ocdialog.js

@@ -210,9 +210,14 @@ $.widget('oc.ocdialog', {
 		}
 
 		const self = this
+		let contentDiv = $('#content')
+		if (contentDiv.length === 0) {
+			// nextcloud-vue compatibility
+			contentDiv = $('.content')
+		}
 		this.overlay = $('<div>')
 			.addClass('oc-dialog-dim')
-			.appendTo($('#content'))
+			.appendTo(contentDiv)
 		this.overlay.on('click keydown keyup', function(event) {
 			if (event.target !== self.$dialog.get(0) && self.$dialog.find($(event.target)).length === 0) {
 				event.preventDefault()