Move ACTION_SIP_INCOMING_CALL back to Manifest

The ACTION_SIP_INCOMING_CALL intent receiver along with
all of the other SIP intent receivers were moved to
dynamic registration because background check
was not letting them be received. Since
ACTION_SIP_INCOMING_CALL is an explicit intent, this
caused this intent to not be received anymore and
caused SIP incoming calls to not show InCall UI.

This change moves that intent back to the manifest
so that it can be received.

Bug: 64508600
Test: Manual
Change-Id: Ie330f748790fc0470a2b59128258c50e17d4cdf7
diff --git a/sip/proguard.flags b/sip/proguard.flags
index 23ae8c1..1c380ed 100644
--- a/sip/proguard.flags
+++ b/sip/proguard.flags
@@ -1,3 +1,3 @@
 -verbose
 -keep class com.android.services.telephony.sip.SipConnectionService
--keep class com.android.services.telephony.sip.SipBroadcastReceiver
+-keep class com.android.services.telephony.sip.SipIncomingCallReceiver