[ECO-5196] Updated Messages.kt

1. Updated Messages interface, added methods for message update and delete

chat-android/src/main/java/com/ably/chat/Messages.kt

@@ -70,6 +70,47 @@ interface Messages : EmitsDiscontinuities {
      */
     suspend fun send(text: String, metadata: MessageMetadata? = null, headers: MessageHeaders? = null): Message
 
+    /**
+     * Update a message in the chat room.
+     *
+     * This method uses the Ably Chat API REST endpoint for updating messages.
+     * It creates a new message with the same serial and a new version.
+     * The original message is not modified.
+     *
+     * @param message The message to update.
+     * @param text The new text of the message.
+     * @param description Optional description for the update action.
+     * @param opMetadata Optional metadata for the update action.
+     * @param metadata Optional metadata of the message.
+     * @param headers Optional headers of the message.
+     * @returns updated message.
+     */
+    suspend fun update(message: Message,
+                       text: String,
+                       description: String? = null,
+                       opMetadata: OperationMetadata? = null,
+                       metadata: MessageMetadata? = null,
+                       headers: MessageHeaders? = null): Message
+
+    /**
+     * Delete a message in the chat room.
+     *
+     * This method uses the Ably Chat API REST endpoint for deleting messages.
+     * It performs a `soft` delete, meaning the message is marked as deleted.
+     *
+     * Should you wish to restore a deleted message, and providing you have the appropriate permissions,
+     * you can simply send an update to the original message.
+     * Note: This is subject to change in future versions, whereby a new permissions model will be introduced
+     * and a deleted message may not be restorable in this way.
+     *
+     * @returns when the message is deleted.
+     * @param message - The message to delete.
+     * @param description - Optional description for the delete action.
+     * @param opMetadata - Optional metadata for the delete action.
+     * @return A promise that resolves to the deleted message.
+     */
+    suspend fun delete(message: Message, description: String? = null, opMetadata: OperationMetadata? = null): Message
+
     /**
      * An interface for listening to new messaging event
      */
@@ -344,6 +385,21 @@ internal class DefaultMessages(
         SendMessageParams(text, metadata, headers),
     )
 
+    override suspend fun update(
+        message: Message,
+        text: String,
+        description: String?,
+        opMetadata: OperationMetadata?,
+        metadata: MessageMetadata?,
+        headers: MessageHeaders?
+    ): Message {
+        TODO("Not yet implemented")
+    }
+
+    override suspend fun delete(message: Message, description: String?, opMetadata: OperationMetadata?): Message {
+        TODO("Not yet implemented")
+    }
+
     private fun requireChannelSerial(): String {
         return channel.properties.channelSerial
             ?: throw clientError("Channel has been attached, but channelSerial is not defined")