Add feature flag for private message deletion.

bramble-api/src/main/java/org/briarproject/bramble/api/FeatureFlags.java

@@ -8,4 +8,6 @@ public interface FeatureFlags {
 	boolean shouldEnableImageAttachments();
 
 	boolean shouldEnableRemoteContacts();
+
+	boolean shouldEnablePrivateMessageDeletion();
 }

bramble-core/src/test/java/org/briarproject/bramble/test/BrambleCoreIntegrationTestModule.java

@@ -29,6 +29,11 @@ public class BrambleCoreIntegrationTestModule {
 			public boolean shouldEnableRemoteContacts() {
 				return true;
 			}
+
+			@Override
+			public boolean shouldEnablePrivateMessageDeletion() {
+				return true;
+			}
 		};
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/AppModule.java

@@ -246,6 +246,11 @@ public class AppModule {
 			public boolean shouldEnableRemoteContacts() {
 				return IS_DEBUG_BUILD;
 			}
+
+			@Override
+			public boolean shouldEnablePrivateMessageDeletion() {
+				return IS_DEBUG_BUILD;
+			}
 		};
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationActivity.java

@@ -356,6 +356,11 @@ public class ConversationActivity extends BriarActivity
 		MenuInflater inflater = getMenuInflater();
 		inflater.inflate(R.menu.conversation_actions, menu);
 
+		// Hide private message deletion action if feature is not enabled
+		if (!featureFlags.shouldEnablePrivateMessageDeletion()) {
+			menu.removeItem(R.id.action_delete_all_messages);
+		}
+
 		// enable introduction action if available
 		observeOnce(viewModel.showIntroductionAction(), this, enable -> {
 			if (enable != null && enable) {

briar-headless/src/main/java/org/briarproject/briar/headless/HeadlessModule.kt

@@ -99,5 +99,6 @@ internal class HeadlessModule(private val appDir: File) {
     internal fun provideFeatureFlags() = object : FeatureFlags {
         override fun shouldEnableImageAttachments() = false
         override fun shouldEnableRemoteContacts() = true
+        override fun shouldEnablePrivateMessageDeletion() = true
     }
 }

briar-headless/src/test/java/org/briarproject/briar/headless/HeadlessTestModule.kt

@@ -66,5 +66,6 @@ internal class HeadlessTestModule(private val appDir: File) {
     internal fun provideFeatureFlags() = object : FeatureFlags {
         override fun shouldEnableImageAttachments() = false
         override fun shouldEnableRemoteContacts() = true
+        override fun shouldEnablePrivateMessageDeletion() = true
     }
 }