[FIX] web: adapt z-index and dimensions of properties field types

In [1], dropdowns were updated and it impacted the properties field edition:
- z-index of the popover opened for the dropdown of a property field type was
  lower than the element it was opened for, resulting in part of the popover
  being hidden.
- img style (dimensions) was not applied as the dropdown list is now a popover
  (sibling instead of child), resulting in bigger images.

This commit fixes the issue by adding a class on the field type selection
popover.

[1]: 7b7a261

task-3834506

closes #159686

X-original-commit: f202f6f
Related: odoo/enterprise#59649
Signed-off-by: Warnon Aurélien (awa) <awa@odoo.com>

addons/web/static/src/views/fields/properties/property_definition.scss

@@ -64,3 +64,12 @@
         }
     }
 }
+
+.o_field_property_definition_type_popover.popover {
+    z-index: $zindex-popover;
+
+    .dropdown-item img {
+        width: 20px;
+        height: 20px;
+    }
+}

addons/web/static/src/views/fields/properties/property_definition.xml

@@ -53,7 +53,7 @@
                                 t-attf-src="/web/static/src/views/fields/properties/icons/{{state.propertyDefinition.type}}.png"/>
                             <span t-out="state.typeLabel"/>
                         </div>
-                        <Dropdown t-else="">
+                        <Dropdown menuClass="'o_field_property_definition_type_popover'" t-else="">
                             <button class="btn btn-link d-flex p-0 w-100" t-att-title="state.typeLabel">
                                 <div class="o_input_dropdown w-100 o_field_property_dropdown">
                                     <img t-attf-src="/web/static/src/views/fields/properties/icons/{{state.propertyDefinition.type}}.png"