[FIX] api: assert cr is a cursor when creating a new environment

`Environment.__new__` expects a Cursor.
Ensure developers pass a Cursor and not another kind of unexpected object.
Passing another object with the same attributes would work during
the creation of the new environment, but then would fail later,
when using the created environment with the wrong `cr` attribute,
with a less comprehensive error.

Task-3796479

closes odoo/odoo#80644

Signed-off-by: Raphael Collet <rco@odoo.com>

odoo/api.py

@@ -508,6 +508,7 @@ class Environment(Mapping):
                 return env
 
         # otherwise create environment, and add it in the set
+        assert isinstance(cr, BaseCursor)
         self = object.__new__(cls)
         self.cr, self.uid, self.context, self.su = self.args = (cr, uid, frozendict(context), su)
         self.uid_origin = uid_origin
@@ -1361,3 +1362,4 @@ class Starred:
 # keep those imports here in order to handle cyclic dependencies correctly
 from odoo import SUPERUSER_ID
 from odoo.modules.registry import Registry
+from .sql_db import BaseCursor