Add Labs screen for beta testing of public features (#5465)

* Add Labs screen:

- Make `Feature` have an `isInLabs` boolean to distinguish private feature flags from public ones.
- Have `FeatureFlagsService` provide the list of available flags.
- Display the labs item in the settings screen only if there are available public features.
- Remove public feature toggles from developer options.
- Implement the labs screen with the public features.
- Add a clear cache step to the threads feature toggle
- Update screenshots

---------

Co-authored-by: ElementBot <android@element.io>

libraries/featureflag/api/src/main/kotlin/io/element/android/libraries/featureflag/api/Feature.kt

@@ -36,4 +36,10 @@ interface Feature {
      * If true: the feature is finished, it will not appear in the developer options screen.
      */
     val isFinished: Boolean
+
+    /**
+     * Whether the feature is only available in Labs (and not in developer options).
+     * Feature flags that set this to `true` can be enabled by any users, not only those that have enabled developer mode.
+     */
+    val isInLabs: Boolean
 }

libraries/featureflag/api/src/main/kotlin/io/element/android/libraries/featureflag/api/FeatureFlagService.kt

@@ -33,4 +33,9 @@ interface FeatureFlagService {
      * is registered
      */
     suspend fun setFeatureEnabled(feature: Feature, enabled: Boolean): Boolean
+
+    /**
+     * @return the list of available (not finished) features that can be toggled.
+     */
+    fun getAvailableFeatures(): List<Feature>
 }

libraries/featureflag/api/src/main/kotlin/io/element/android/libraries/featureflag/api/FeatureFlags.kt

@@ -19,6 +19,7 @@ enum class FeatureFlags(
     override val description: String? = null,
     override val defaultValue: (BuildMeta) -> Boolean,
     override val isFinished: Boolean,
+    override val isInLabs: Boolean = false,
 ) : Feature {
     RoomDirectorySearch(
         key = "feature.roomdirectorysearch",
@@ -98,6 +99,7 @@ enum class FeatureFlags(
         description = "Renders thread messages as a dedicated timeline. Restarting the app is required for this setting to fully take effect.",
         defaultValue = { false },
         isFinished = false,
+        isInLabs = true,
     ),
     MultiAccount(
         key = "feature.multi_account",

libraries/featureflag/impl/src/main/kotlin/io/element/android/libraries/featureflag/impl/DefaultFeatureFlagService.kt

@@ -14,6 +14,7 @@ import dev.zacsweers.metro.SingleIn
 import io.element.android.libraries.core.meta.BuildMeta
 import io.element.android.libraries.featureflag.api.Feature
 import io.element.android.libraries.featureflag.api.FeatureFlagService
+import io.element.android.libraries.featureflag.api.FeatureFlags
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.flowOf
 
@@ -40,4 +41,8 @@ class DefaultFeatureFlagService(
             ?.let { true }
             ?: false
     }
+
+    override fun getAvailableFeatures(): List<Feature> {
+        return FeatureFlags.entries.filter { !it.isFinished }
+    }
 }

libraries/featureflag/test/src/main/java/io/element/android/libraries/featureflag/test/FakeFeature.kt

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2025 New Vector Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.featureflag.test
+
+import io.element.android.libraries.core.meta.BuildMeta
+import io.element.android.libraries.featureflag.api.Feature
+
+data class FakeFeature(
+    override val key: String,
+    override val title: String,
+    override val description: String? = null,
+    override val defaultValue: (BuildMeta) -> Boolean = { false },
+    override val isFinished: Boolean = false,
+    override val isInLabs: Boolean = false,
+) : Feature

libraries/featureflag/test/src/main/java/io/element/android/libraries/featureflag/test/FakeFeatureFlagService.kt

@@ -17,6 +17,7 @@ import kotlinx.coroutines.flow.MutableStateFlow
 class FakeFeatureFlagService(
     initialState: Map<String, Boolean> = emptyMap(),
     private val buildMeta: BuildMeta = aBuildMeta(),
+    var providedAvailableFeatures: List<Feature> = emptyList(),
 ) : FeatureFlagService {
     private val enabledFeatures = initialState
         .mapValues { MutableStateFlow(it.value) }
@@ -31,4 +32,8 @@ class FakeFeatureFlagService(
     override fun isFeatureEnabledFlow(feature: Feature): Flow<Boolean> {
         return enabledFeatures.getOrPut(feature.key) { MutableStateFlow(feature.defaultValue(buildMeta)) }
     }
+
+    override fun getAvailableFeatures(): List<Feature> {
+        return providedAvailableFeatures
+    }
 }

libraries/featureflag/ui/src/main/kotlin/io/element/android/libraries/featureflag/ui/model/FeatureUiModel.kt

@@ -7,9 +7,12 @@
 
 package io.element.android.libraries.featureflag.ui.model
 
+import io.element.android.libraries.designsystem.theme.components.IconSource
+
 data class FeatureUiModel(
     val key: String,
     val title: String,
     val description: String?,
+    val icon: IconSource?,
     val isEnabled: Boolean
 )

libraries/featureflag/ui/src/main/kotlin/io/element/android/libraries/featureflag/ui/model/FeatureUiModelProvider.kt

@@ -12,7 +12,7 @@ import kotlinx.collections.immutable.persistentListOf
 
 fun aFeatureUiModelList(): ImmutableList<FeatureUiModel> {
     return persistentListOf(
-        FeatureUiModel("key1", "Display State Events", "Show state events in the timeline", true),
-        FeatureUiModel("key2", "Display Room Events", null, false),
+        FeatureUiModel(key = "key1", title = "Display State Events", description = "Show state events in the timeline", icon = null, isEnabled = true),
+        FeatureUiModel(key = "key2", title = "Display Room Events", description = null, icon = null, isEnabled = false),
     )
 }