ADS: Re-enable ADS Preview (#6819)

Task/Issue URL:
https://app.asana.com/1/137249556945/project/1202552961248957/task/1211407136075484?focus=true

### Description
Re-enable ADS demo screen


### Steps to test this PR

_ADS Demo_
- [x] Install Internal flavour
- [x] Navigate to Settings and verify ADS Demo is visible
- [x] Open it and verify it works

Author: malmstein

design-system/build.gradle

@@ -43,6 +43,7 @@ dependencies {
     anvil project(path: ':anvil-compiler')
     implementation project(path: ':anvil-annotations')
     implementation project(path: ':app-build-config-api')
+    implementation project(':internal-features-api')
     implementation "androidx.datastore:datastore-preferences:_"
 
     implementation AndroidX.appCompat

design-system/src/main/java/com/duckduckgo/common/ui/themepreview/ui/AppComponentsSettingsFeature.kt

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2025 DuckDuckGo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.duckduckgo.common.ui.themepreview.ui
+
+import android.content.Context
+import com.duckduckgo.anvil.annotations.PriorityKey
+import com.duckduckgo.di.scopes.AppScope
+import com.duckduckgo.internal.features.api.InternalFeaturePlugin
+import com.duckduckgo.mobile.android.R as CommonR
+import com.squareup.anvil.annotations.ContributesMultibinding
+import javax.inject.Inject
+
+@ContributesMultibinding(AppScope::class)
+@PriorityKey(InternalFeaturePlugin.ADS_SETTINGS_PRIO_KEY)
+class ThemesPreviewInternalFeature @Inject constructor(private val context: Context) : InternalFeaturePlugin {
+
+    override fun internalFeatureTitle(): String {
+        return context.getString(CommonR.string.ads_demo_plugin_title)
+    }
+
+    override fun internalFeatureSubtitle(): String {
+        return context.getString(CommonR.string.ads_demo_plugin_message)
+    }
+
+    override fun onInternalFeatureClicked(activityContext: Context) {
+        activityContext.startActivity(AppComponentsActivity.intent(activityContext))
+    }
+}

design-system/src/main/res/values/donottranslate.xml

@@ -30,6 +30,9 @@
     <string name="ads_demo_activity_title" translatable="false">Android Design System Demo</string>
     <string name="ads_demo_header_title" translatable="false">Android Design System</string>
 
+    <!-- ADS Demo Screen -->
+    <string name="ads_demo_plugin_title" translatable="false">Android Design System Preview</string>
+    <string name="ads_demo_plugin_message" translatable="false">Set of components designed following our Design System</string>
 
     <!--Components-->
     <string name="text_headline" translatable="false">Headline</string>

internal-features/internal-features-api/src/main/java/com/duckduckgo/internal/features/api/InternalFeaturePlugin.kt

@@ -34,7 +34,6 @@ interface InternalFeaturePlugin {
 
     // Every time you want to add a setting add the priority (order) to the list below and use it in the plugin
     companion object {
-        const val EXPERIMENTAL_UI_SETTINGS = 99
         const val DEVELOPER_SETTINGS_PRIO_KEY = 100
         const val FEATURE_INVENTORY_PRIO_KEY = 110
         const val SYNC_SETTINGS_PRIO_KEY = 200