Add monitor related code

Bug: 261877110
Test: Telecom unit test
Change-Id: I05258c0ce17de38fb220f97ddbdda75a6bab1a1f
Merged-In: I05258c0ce17de38fb220f97ddbdda75a6bab1a1f

telecomm/java/android/telecom/CallAttributes.java

@@ -58,6 +58,9 @@ public final class CallAttributes implements Parcelable {
     /** @hide **/
     public static final String CALL_CAPABILITIES_KEY = "TelecomCapabilities";
 
+    /** @hide **/
+    public static final String CALLER_PID = "CallerPid";
+
     private CallAttributes(@NonNull PhoneAccountHandle phoneAccountHandle,
             @NonNull CharSequence displayName,
             @NonNull Uri address,