[FIX] ir_property: fix implementation of property field search

To search a property field of type 'many2one':
 - first retrieve records from the comodel that match the condition,
 - then search properties with value_reference in the refs of the records,
 - finally retrieve the model records that correspond to matching properties.

The fixes:
 - retrieve records in the comodel with name_search() instead of search()
 - generate refs for the records with the comodel instead of the model