Add API to get the telecom call id from Call.Details.

This CL unhides StreamingCall#EXTRA_CALL_ID and adds an API to Call Details to get the telecom call ID. Updated CTS tests accordingly to account for these changes.

Fixes: 286457948
Test: atest CallDetailsTest && atest CallStreamingTest
Change-Id: Ibf9dbe38224b9710eb79aa68812f3a185f7e297d
diff --git a/telecomm/java/android/telecom/Call.java b/telecomm/java/android/telecom/Call.java
index 1da4ea9..78b86d3 100644
--- a/telecomm/java/android/telecom/Call.java
+++ b/telecomm/java/android/telecom/Call.java
@@ -936,6 +936,12 @@
             return mState;
         }
 
+        /**
+         * @return the Telecom identifier associated with this {@link Call} . This is not a stable
+         * identifier and is not guaranteed to be unique across device reboots.
+         */
+        public @NonNull String getId() { return mTelecomCallId; }
+
         /** {@hide} */
         @TestApi
         public String getTelecomCallId() {