[FIX] base: fix dev mode for get_view_arch_from_file and inherits

Before this commits, dev mode crash in some case (see below) when you declare
a website_page without field name='arch'.
After this commit, we follow the view_id (limit: only into the same file)

Contactus works luckily before this commit, because compute field xml_id on
View return the first ir_model_data (order by name asc by default).

website.contactus
    is BEFORE
website.contactus_page_ir_ui_view

 -- while --

website.bs_debug_page_view
    is AFTER
website.contactus_page_ir_ui_view

closes odoo/odoo#27234

odoo/addons/base/ir/ir_ui_view.py

@@ -127,6 +127,13 @@ def get_view_arch_from_file(filename, xmlid):
         if node.tag in ('template', 'record'):
             if node.tag == 'record':
                 field = node.find('field[@name="arch"]')
+                if field is None:
+                    if node.find('field[@name="view_id"]') is not None:
+                        view_id = node.find('field[@name="view_id"]').attrib.get('ref')
+                        ref_id = '%s%s' % ('.' not in view_id and xmlid.split('.')[0] + '.' or '', view_id)
+                        return get_view_arch_from_file(filename, ref_id)
+                    else:
+                        return None
                 _fix_multiple_roots(field)
                 inner = u''.join([etree.tostring(child, encoding='unicode') for child in field.iterchildren()])
                 return field.text + inner