Write new flags to proto messages for callables

This is needed to get rid of two unused bits: Flags.RESERVED_1 and
Flags.RESERVED_2. The old flags are still there temporarily because of the
bootstrap dependency on built-ins. Soon the old flags will be dropped and the
current flags will be transformed to the new format

core/deserialization/src/descriptors.proto

@@ -222,7 +222,7 @@ message Constructor {
     Visibility
     isSecondary
   */
-  optional int32 flags = 1 [default = 6];
+  optional int32 flags = 1 [default = 6 /* public constructor, no annotations */];
 
   repeated ValueParameter value_parameter = 2;
 
@@ -242,6 +242,7 @@ message Function {
     isExternal
   */
   optional int32 flags = 1 [default = 6];
+  optional int32 new_flags = 9 [default = 6 /* public final function, no annotations */];
 
   required int32 name = 2 [(name_id_in_table) = true];
 
@@ -273,7 +274,8 @@ message Property {
     lateinit
     hasConstant
   */
-  optional int32 flags = 1 [default = 262 /* public (6) final property with getter (256) */];
+  optional int32 flags = 1 [default = 262];
+  optional int32 new_flags = 11 [default = 518 /* public (6) final property with getter (512) */];
 
   required int32 name = 2 [(name_id_in_table) = true];