Fix copying multi-line selected rich text

For rich text (rendered HTML) fields and areas, the selectedText
property for some reason contains "\u2028" or "\u2029"
characters that look like newlines in Qt programs but are just
invisible anywhere else. Translate them to normal "\n".

src/gui/DebugConsole.qml

@@ -208,9 +208,9 @@ HDrawer {
 
                 Layout.fillWidth: true
 
-                onSelectedTextChanged: if (selectedText) {
+                onSelectedTextChanged: if (selectedPlainText) {
                     selectedOutputDelegateIndex = model.index
-                    selectedOutputText          = selectedText
+                    selectedOutputText          = selectedPlainText
                 } else if (selectedOutputDelegateIndex === model.index) {
                     selectedOutputDelegateIndex = -1
                     selectedOutputText          = ""
@@ -249,7 +249,7 @@ HDrawer {
                         icon.name: "copy-text"
                         text: qsTr("Copy")
                         onTriggered: {
-                            if (delegate.selectedText) {
+                            if (delegate.selectedPlainText) {
                                 delegate.copy()
                                 return
                             }
@@ -337,7 +337,7 @@ HDrawer {
             Keys.onPressed: ev => {
                 if (
                     ev.matches(StandardKey.Copy) &&
-                    ! inputArea.selectedText &&
+                    ! inputArea.selectedPlainText &&
                     selectedOutputText
                 ) {
                     ev.accepted = true