[IMP] web: improve Edit Translations button

Previously, 'Edit Translations' button is used to translate
the English field ir_ui_view.arch
A dialog for list view of all translations is opened

After this commit, a new 'EN' button is used to translate
the Engligsh field ir_ui_view.arch
A translation dialog (like other translatable fields) for all translations is opened

General idea of the implementation:
1. add the invisible ir_ui_view.arch_db field to the form view before ir_ui_view.arch
2. show the 'Lang' button in the edit mode
   and make it look like a button for its next field ir_ui_view.arch
3. Forcely change the 'Lang' button to 'EN'

addons/web/static/src/legacy/scss/form_view.scss

@@ -713,6 +713,20 @@ $o-form-label-margin-right: 0px;
             padding-right: 25px;
         }
     }
+    .oe_no_translation_content {
+        &:not(.btn) {
+            display: none;
+        }
+        &.btn {
+            width: 100% !important;
+            margin-left: 0px;
+            visibility: hidden;
+        }
+        &.btn:after {
+            content: 'EN';
+            visibility: visible;
+        }
+    }
 
     // Text field with oe_inline class
     .o_field_text.oe_inline {

addons/web/static/src/views/form/form_controller.scss

@@ -436,6 +436,20 @@ $o-form-label-margin-right: 0px;
             padding-right: 25px;
         }
     }
+    .oe_no_translation_content {
+        :not(.btn) {
+            display: none;
+        }
+        .btn {
+            width: 100% !important;
+            margin-left: 0px;
+            visibility: hidden;
+        }
+        .btn:after {
+            content: 'EN';
+            visibility: visible;
+        }
+    }
     iframe.wysiwyg_iframe + .o_field_translate {
         right: 30px !important;
         top: 7px !important;

odoo/addons/base/models/ir_ui_view.py

@@ -2037,10 +2037,6 @@ actual arch.
     # Misc
     #------------------------------------------------------
 
-    def open_translations(self):
-        """ Open a view for editing the translations of field 'arch_db'. """
-        return self.env['ir.translation'].translate_fields('ir.ui.view', self.id, 'arch_db')
-
     @api.model
     def _validate_custom_views(self, model):
         """Validate architecture of custom views (= without xml id) for a given model.

odoo/addons/base/views/ir_ui_view_views.xml

@@ -28,8 +28,7 @@
                     </div>
                     <notebook>
                         <page string="Architecture" name="architecture">
-                            <button type="object" name="open_translations"
-                                string="Edit Translations" class="oe_link oe_right"/>
+                            <field name="arch_db" class="oe_no_translation_content"/>
                             <field name="arch_base" string="View Architecture" widget="ace" options="{'mode': 'xml'}" required="1"/>
                         </page>
                         <page string="Access Rights" name="access_rights">