feat(common): expose 'unstable' option in generated code

common/protob/pb2py

@@ -327,6 +327,8 @@ class Descriptor:
         if msg_id is None:
             msg_id = self.message_types.get(message.name)
 
+        unstable = self._get_extension(message, "unstable")
+
         # "from .. import protobuf as p"
         yield self.protobuf_import + " as p"
 
@@ -358,6 +360,9 @@ class Descriptor:
         if msg_id is not None:
             yield "    MESSAGE_WIRE_TYPE = {}".format(msg_id)
 
+        if unstable is not None:
+            yield "    UNSTABLE = True"
+
         if fields:
             yield ""
             yield from self.create_init_method(fields)

core/src/trezor/messages/AuthorizeCoinJoin.py

@@ -13,6 +13,7 @@ if __debug__:
 
 class AuthorizeCoinJoin(p.MessageType):
     MESSAGE_WIRE_TYPE = 51
+    UNSTABLE = True
 
     def __init__(
         self,

python/src/trezorlib/messages/AuthorizeCoinJoin.py

@@ -13,6 +13,7 @@ if __debug__:
 
 class AuthorizeCoinJoin(p.MessageType):
     MESSAGE_WIRE_TYPE = 51
+    UNSTABLE = True
 
     def __init__(
         self,