MainActivity fixes (#6591)

* Reduce notifyDataSetChanged calls when category count is disabled

* Fix category tabs briefly showing when it's supposed to be disabled

Also fix tabs showing when activity recreated

* Lift appbar when tab is hidden

Check against tab visibility instead of viewpager

* Restore selected nav item after recreate

* Simplify SHORTCUT_MANGA intent handling

Don't need to change controller if the topmost controller is the target

app/src/main/java/eu/kanade/tachiyomi/ui/base/controller/TabbedController.kt

@@ -4,7 +4,10 @@ import com.google.android.material.tabs.TabLayout
 
 interface TabbedController {
 
-    fun configureTabs(tabs: TabLayout) {}
+    /**
+     * @return true to let activity updates tabs visibility (to visible)
+     */
+    fun configureTabs(tabs: TabLayout): Boolean = true
 
     fun cleanupTabs(tabs: TabLayout) {}
 }