Initial setup for Settings page redesign with debug settings

- Added a new settings option to enable the settings page redesign.
- This option allows us to integrate and test the new settings page
  gradually, minimizing disruptions to the current behavior.
- Reused the rest of the debug menu to reflect in the new settings page.
- Verified the functionality of all debug settings.

Next plan:
- Create PRs to gradually add all the subsections as detailed in
  https://github.com/TeamNewPipe/NewPipe/issues/9587.

Note:
- This PR prepares for upcoming updates by setting up the necessary
  changes for follow-up PRs.

app/src/main/java/org/schabi/newpipe/settings/MainSettingsV2Fragment.kt

@@ -0,0 +1,49 @@
+package org.schabi.newpipe.settings
+
+import android.os.Bundle
+import android.view.Menu
+import android.view.MenuInflater
+import android.view.MenuItem
+import androidx.activity.ComponentActivity
+import androidx.core.view.MenuProvider
+import androidx.preference.Preference
+import org.schabi.newpipe.R
+
+/**
+ *  Provides main settings page, entry point to the NewPipe app settings.
+ */
+class MainSettingsV2Fragment : BasePreferenceFragment(), MenuProvider {
+    override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
+        addPreferencesFromResourceRegistry()
+
+        (activity as? ComponentActivity)?.addMenuProvider(this, this)
+
+        // Hide debug preferences in RELEASE build variant
+        if (!DEBUG) {
+            findPreference<Preference>(getString(R.string.debug_pref_screen_key))?.let(
+                preferenceScreen::removePreference,
+            )
+        }
+    }
+
+    override fun onCreateMenu(menu: Menu, menuInflater: MenuInflater) {
+        // -- Link settings activity and register menu --
+        menuInflater.inflate(R.menu.menu_settings_main_fragment, menu)
+        val menuSearchItem = menu.getItem(0)
+        (activity as? SettingsActivity)?.setMenuSearchItem(menuSearchItem)
+    }
+
+    override fun onMenuItemSelected(menuItem: MenuItem): Boolean {
+        if (menuItem.itemId == R.id.action_search) {
+            (activity as? SettingsActivity)?.setSearchActive(true)
+            return true
+        }
+        return false
+    }
+
+    override fun onDestroy() {
+        // Unlink activity so that we don't get memory problems
+        (activity as? SettingsActivity)?.setMenuSearchItem(null)
+        super.onDestroy()
+    }
+}

app/src/main/java/org/schabi/newpipe/settings/SettingsActivity.java

@@ -20,6 +20,7 @@ import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentManager;
 import androidx.preference.Preference;
 import androidx.preference.PreferenceFragmentCompat;
+import androidx.preference.PreferenceManager;
 
 import com.jakewharton.rxbinding4.widget.RxTextView;
 
@@ -112,8 +113,14 @@ public class SettingsActivity extends AppCompatActivity implements
                 }
             }
         } else {
+            final boolean shouldDisplaySettingsRedesign = PreferenceManager
+                    .getDefaultSharedPreferences(this)
+                    .getBoolean(getString(R.string.settings_layout_redesign_key), false);
+            final BasePreferenceFragment mainSettingsFragment =
+                    shouldDisplaySettingsRedesign
+                            ? new MainSettingsV2Fragment() : new MainSettingsFragment();
             getSupportFragmentManager().beginTransaction()
-                    .replace(R.id.settings_fragment_holder, new MainSettingsFragment())
+                    .replace(R.id.settings_fragment_holder, mainSettingsFragment)
                     .commit();
         }
 

app/src/main/java/org/schabi/newpipe/settings/SettingsResourceRegistry.java

@@ -29,6 +29,10 @@ public final class SettingsResourceRegistry {
     private final Set<SettingRegistryEntry> registeredEntries = new HashSet<>();
 
     private SettingsResourceRegistry() {
+        add(MainSettingsV2Fragment.class, R.xml.main_settings_v2).setSearchable(false);
+
+        // Before redesign settings arrangement. These should be cleared once the
+        // settings_layout_redesign_key is approved and enabled by default.
         add(MainSettingsFragment.class, R.xml.main_settings).setSearchable(false);
 
         add(AppearanceSettingsFragment.class, R.xml.appearance_settings);

app/src/main/res/values/settings_keys.xml

@@ -245,6 +245,7 @@
     <string name="crash_the_app_key">crash_the_app_key</string>
     <string name="show_error_snackbar_key">show_error_snackbar_key</string>
     <string name="create_error_notification_key">create_error_notification_key</string>
+    <string name="settings_layout_redesign_key">settings_layout_redesign_key</string>
 
     <!-- THEMES -->
     <string name="theme_key">theme</string>

app/src/main/res/values/strings.xml

@@ -491,6 +491,7 @@
     <string name="crash_the_app">Crash the app</string>
     <string name="show_error_snackbar">Show an error snackbar</string>
     <string name="create_error_notification">Create an error notification</string>
+    <string name="settings_layout_redesign">Enable the Redesigned Settings page</string>
     <!-- Subscriptions import/export -->
     <string name="import_title">Import</string>
     <string name="import_from">Import from</string>

app/src/main/res/xml/debug_settings.xml

@@ -71,4 +71,11 @@
         android:title="@string/create_error_notification"
         app:singleLineTitle="false"
         app:iconSpaceReserved="false" />
+
+    <SwitchPreferenceCompat
+        android:defaultValue="false"
+        android:key="@string/settings_layout_redesign_key"
+        android:title="@string/settings_layout_redesign"
+        app:iconSpaceReserved="false"
+        app:singleLineTitle="false" />
 </PreferenceScreen>

app/src/main/res/xml/main_settings_v2.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:key="general_preferences"
+    android:title="@string/settings">
+
+    <PreferenceScreen
+        android:fragment="org.schabi.newpipe.settings.DebugSettingsFragment"
+        android:key="@string/debug_pref_screen_key"
+        android:title="@string/settings_category_debug_title"
+        app:iconSpaceReserved="false" />
+</PreferenceScreen>