support for datatype in newer sync schemas

In Model converter, also validate messages in message_to_odoo.

Model converter argument changed, __type__ is now the last argument and is optional. It is expected not to be used anymore. Added possible_datatypes property and odoo_datatype on Converter. Defaults to empty set and None. On Model, it can be set.

Replace generic exceptions.

tests/test_base.py

@@ -60,7 +60,6 @@
             Field("name"),
         )
         converter = Model(
-            "res.users",
             {
                 "user_creator_name": rel,
             },
@@ -64,6 +63,7 @@
             {
                 "user_creator_name": rel,
             },
+            __type__="res.users",
         )
         with self.assertRaises(UserError) as e:
             converter.odoo_to_message(self.active_user)
@@ -84,7 +84,6 @@
 
     def test_convert(self):
         converter = Model(
-            None,
             {
                 "active": Field("active"),
                 "ref": Xref("base"),