[FIX] base: split _get_rendering_context to allow different models

Allowing to override the _get_rendering_context and call the new
function (_get_rendreing_context_model) with a different custom model
to render the html.

opw-1946792

closes odoo/odoo#32101

Signed-off-by: Jorge Pinna Puissant (jpp) <jpp@odoo.com>

odoo/addons/base/models/ir_actions_report.py

@@ -721,12 +721,16 @@ class IrActionsReport(models.Model):
         data = self._get_rendering_context(docids, data)
         return self.render_template(self.report_name, data), 'html'
 
+    @api.model
+    def _get_rendering_context_model(self):
+        report_model_name = 'report.%s' % self.report_name
+        return self.env.get(report_model_name)
+
     @api.model
     def _get_rendering_context(self, docids, data):
         # If the report is using a custom model to render its html, we must use it.
         # Otherwise, fallback on the generic html rendering.
-        report_model_name = 'report.%s' % self.report_name
-        report_model = self.env.get(report_model_name)
+        report_model = self._get_rendering_context_model()
 
         data = data and dict(data) or {}