Resolve Tryton modules using entrypoints

The Pool tries to resolve registered string using the path `trytond.modules.`
which can not always be imported if the module is using an entry pointing to
another package.

Closes #14914
(grafted from bb96325e829df570aac1f7624c862a660c0be286)

--HG--
branch : 8.0

trytond/trytond/tools/misc.py

@@ -177,8 +177,15 @@ def is_instance_method(cls, method):
 def resolve(name):
     "Resolve a dotted name to a global object."
     name = name.split('.')
-    used = name.pop(0)
-    found = importlib.import_module(used)
+    if name[:2] == ['trytond', 'modules']:
+        # import the Tryton module using entry point
+        name = name[2:]
+        used = name.pop(0)
+        found = import_module(used)
+        used = found.__name__
+    else:
+        used = name.pop(0)
+        found = importlib.import_module(used)
     for n in name:
         used = used + '.' + n
         try: