Refine mobileform settings

Numerous refinements to the new mobileform setting pages 
- Ensure left and right padding at the top level is 0 for mobile
- Centre align the avatar in the account editor page and add tooltip to button
- Fix the bubble/compact mode setting so that it fits when thin, i.e on mobile
- Fix the loading placeholder in device settings

src/qml/Settings/AppearanceSettingsPage.qml

@@ -26,13 +26,18 @@ Kirigami.ScrollablePage {
                 }
 
                 MobileForm.AbstractFormDelegate {
+                    id: timelineModeSetting
                     Layout.fillWidth: true
                     background: Item {}
                     contentItem: RowLayout {
                         Layout.alignment: Qt.AlignCenter
-                        spacing: Kirigami.Units.gridUnit * 2
+                        spacing: Kirigami.Units.largeSpacing
+                        Item {
+                            Layout.fillWidth: true
+                        }
                         QQC2.ButtonGroup { id: themeGroup }
                         ThemeRadioButton {
+                            thin: timelineModeSetting.width < Kirigami.Units.gridUnit * 22
                             innerObject: [
                                 RowLayout {
                                     Layout.fillWidth: true
@@ -121,7 +126,8 @@ Kirigami.ScrollablePage {
                             }
                         }
                         ThemeRadioButton {
-                            Layout.alignment: Qt.AlignRight
+                            // Layout.alignment: Qt.AlignRight
+                            thin: timelineModeSetting.width < Kirigami.Units.gridUnit * 22
                             innerObject: [
                                 RowLayout {
                                     Layout.fillWidth: true
@@ -188,6 +194,9 @@ Kirigami.ScrollablePage {
                                 Config.save();
                             }
                         }
+                        Item {
+                            Layout.fillWidth: true
+                        }
                     }
                 }
             }