Send legacy private messages from headless app.

briar-headless/src/main/java/org/briarproject/briar/headless/messaging/MessagingControllerImpl.kt

@@ -73,7 +73,7 @@ constructor(
 
         val group = messagingManager.getContactGroup(contact)
         val now = clock.currentTimeMillis()
-        val m = privateMessageFactory.createPrivateMessage(group.id, now, text, emptyList())
+        val m = privateMessageFactory.createLegacyPrivateMessage(group.id, now, text)
 
         messagingManager.addLocalMessage(m)
         return ctx.json(m.output(contact.id, text))

briar-headless/src/test/java/org/briarproject/briar/headless/messaging/MessagingControllerImplTest.kt

@@ -115,11 +115,10 @@ internal class MessagingControllerImplTest : ControllerTest() {
         every { messagingManager.getContactGroup(contact) } returns group
         every { clock.currentTimeMillis() } returns timestamp
         every {
-            privateMessageFactory.createPrivateMessage(
+            privateMessageFactory.createLegacyPrivateMessage(
                 group.id,
                 timestamp,
-                text,
-                emptyList()
+                text
             )
         } returns privateMessage
         every { messagingManager.addLocalMessage(privateMessage) } just runs