[FIX] web: form: display larger title fields

In form views, we want the fields displayed in the "oe_title" div
to take full width. It worked before because we have a rule in
webclient that applies on all almost all kinds of inputs (text,
number,phone...). However, since we wrap fields in a div, those
rules no longer have the wanted effect in our particular usecase.
This commit is a heuristic, but it should solve most of the cases.
It applies on all char fields displayed as title.

Part-of: odoo/odoo#99503

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

@@ -102,7 +102,8 @@ $o-form-label-margin-right: 0px;
         }
     }
 
-    .o_row > div > .o_field_widget {
+    .o_row > div > .o_field_widget,
+    &.o_form_editable .oe_title .o_field_char {
         width: 100%;
     }