Group on company currency in sale reporting

It is needed to construct unique ID when grouping by other mean than the line id.
Also the revenue is computed in the company currency.

Closes #13744

modules/sale/sale_reporting.py

@@ -136,7 +136,7 @@ class Abstract(ModelSQL):
             line.company.as_('company'),
             revenue.as_('revenue'),
             Count(line.order, distinct=True).as_('number'),
-            line.currency.as_('currency'),
+            currency.id.as_('currency'),
             ]
 
     @classmethod
@@ -148,7 +148,7 @@ class Abstract(ModelSQL):
     def _group_by(cls, tables, withs):
         line = tables['line']
         currency = tables['line.company.currency']
-        return [line.company, line.currency, currency.digits]
+        return [line.company, currency.id, currency.digits]
 
     @classmethod
     def _where(cls, tables, withs):