UI: settings show/hide update display (#1072)

* UI: settings show/hide update display

This PR replaces the PR #1003

In this PR, the visual for available update is added to the foreground.

There are new settings to generally show/hide the update display, and only administrators receive the update display.

* change to `Bean`

* Update AppUpdateShowService.java

* add update message

* revision service

* change shouldShow

* Update githubVersion.js

* rm folder

* Update AppUpdateService.java

src/main/java/stirling/software/SPDF/config/ShowAdminInterface.java

@@ -0,0 +1,7 @@
+package stirling.software.SPDF.config;
+
+public interface ShowAdminInterface {
+    default boolean getShowUpdateOnlyAdmins() {
+        return true;
+    }
+}