Add publishDTMF method for Sending DTMF signals to SIP Participant (#576)

* Update LocalParticipant.kt

Add publishDTMF command.

* Update LocalParticipant.kt

* spotless apply and setKind

* Create hungry-peas-bow.md

---------

Co-authored-by: David Zhao <dz@livekit.io>

+---
+"client-sdk-android": patch
+---
+
+Add publishDTMF method for Sending DTMF signals to SIP Participant

@@ -736,6 +736,34 @@ internal constructor(
     }
 
     /**
+     * This suspend function allows you to publish DTMF (Dual-Tone Multi-Frequency)
+     * signals within a LiveKit room. The `publishDtmf` function constructs a
+     * SipDTMF message using the provided code and digit, then encapsulates it
+     * in a DataPacket before sending it via the engine.
+     *
+     * Parameters:
+     *  - code: an integer representing the DTMF signal code
+     *  - digit: the string representing the DTMF digit (e.g., "1", "#", "*")
+     */
+
+    @Suppress("unused")
+    suspend fun publishDtmf(
+        code: Int,
+        digit: String,
+    ) {
+        val sipDTMF = LivekitModels.SipDTMF.newBuilder().setCode(code)
+            .setDigit(digit)
+            .build()
+
+        val dataPacket = LivekitModels.DataPacket.newBuilder()
+            .setSipDtmf(sipDTMF)
+            .setKind(LivekitModels.DataPacket.Kind.RELIABLE)
+            .build()
+
+        engine.sendData(dataPacket)
+    }
+
+    /**
      * @suppress
      */
     @VisibleForTesting