multi: add zero-conf, scid-alias channel-types to rpc

This allows the open channel rpcs to use the zero-conf or scid-alias
channel types.

lnrpc/lightning.proto

@@ -2121,6 +2121,17 @@ message OpenChannelRequest {
     the remote peer supports explicit channel negotiation.
     */
     CommitmentType commitment_type = 18;
+
+    /*
+    If this is true, then a zero-conf channel open will be attempted.
+    */
+    bool zero_conf = 19;
+
+    /*
+    If this is true, then an option-scid-alias channel-type open will be
+    attempted.
+    */
+    bool scid_alias = 20;
 }
 message OpenStatusUpdate {
     oneof update {