First attempt at supporting multicast resource guarantees.

proto/p4/config/v1/p4info.proto

@@ -73,6 +73,15 @@ message PkgInfo {
   string url = 8;
   // Miscellaneous metadata, structured; a way to extend PkgInfo
   repeated StructuredAnnotation structured_annotations = 9;
+  // Max number of multicast entries (i.e. multicast groups).
+  // If 0, there are no known guarantees.
+  int64 multicast_table_size = 11;
+  // The total number of replicas available across all  groups.
+  // If 0, there are no known guarantees.
+  int64 multicast_table_max_replicas = 12;
+  // The maximum number of replicas that can be used per group/entry.
+  // If 0, `multicast_table_max_replicas` should be used.
+  int64 multicast_table_max_replicas_per_entry = 13;
 }
 
 // wrapping the enum in a message to avoid name collisions in C++, where "enum