Add a ToggleSwitch and use it for SettingsFlag

Also bring in the compact timeline option.

Without minor CSS changes, the old user settings are completely unusable with this change. As such, minimal effort has been put in to have it be useful. Similarly, the changes drop the use of radio groups and the old theme selector was the only one that used it. See the comments for more details on how/why this was mitigated the way it was.

res/css/structures/_UserSettings.scss

@@ -255,3 +255,15 @@ input.mx_UserSettings_phoneNumberField {
 .mx_UserSettings_analyticsModal table {
     margin: 10px 0px;
 }
+
+
+// Temp styles to keep the layout moderately usable. Not perfect, but better
+// than 30 options being impossible to understand.
+.mx_UserSettings .mx_SettingsFlag {
+    height: 30px;
+}
+
+.mx_UserSettings .mx_SettingsFlag .mx_ToggleSwitch {
+    float: left;
+    margin-right: 5px;
+}