Move AudioPage.qml into separate directory

This encapsulates the page and separates it and the files it uses from
the rest of the application.

src/res/qml/RootPage.qml

@@ -4,6 +4,7 @@ import QtQuick.Layouts 1.3
 import matzman666.advsettings 1.0
 import "." // QTBUG-34418, singletons require explicit import to load qmldir file
 import "utilities_page"
+import "audio_page"
 
 MyStackViewPage {
     id: rootPage
@@ -342,7 +343,7 @@ MyStackViewPage {
                            Layout.leftMargin: 12
                            checkable: true
                            contentItem: Image {
-                               source: parent.checked ? "mic_off.svg" : "mic_on.svg"
+                               source: parent.checked ? "audio_page/mic_off.svg" : "audio_page/mic_on.svg"
                                sourceSize.width: 32
                                sourceSize.height: 32
                                anchors.fill: parent