drop buttons_data argument from ButtonWithDropdown in favour of passing Button instances

If Button instances are going to be our standard mechanism for passing the bundle of properties for a menu item, we don't need to invent another one.

wagtail/admin/templatetags/wagtailadmin_tags.py

@@ -39,7 +39,7 @@ from wagtail.admin.utils import (
     get_valid_next_url_from_request,
 )
 from wagtail.admin.views.bulk_action.registry import bulk_action_registry
-from wagtail.admin.widgets import ButtonWithDropdown, PageListingButton
+from wagtail.admin.widgets import Button, ButtonWithDropdown, PageListingButton
 from wagtail.coreutils import (
     camelcase_to_underscore,
     escape_script,
@@ -540,19 +540,19 @@ def bulk_action_choices(context, app_label, model_name):
             label=_("More"),
             attrs={"title": _("More bulk actions")},
             button_classes={"button", "button-secondary", "button-small"},
-            buttons_data=[
-                {
-                    "label": action.display_name,
-                    "url": reverse(
+            buttons=[
+                Button(
+                    label=action.display_name,
+                    url=reverse(
                         "wagtail_bulk_action",
                         args=[app_label, model_name, action.action_type],
                     )
                     + "?"
                     + urlencode({"next": next_url}),
-                    "attrs": {"aria-label": action.aria_label},
-                    "priority": action.action_priority,
-                    "classes": {"bulk-action-btn"},
-                }
+                    attrs={"aria-label": action.aria_label},
+                    priority=action.action_priority,
+                    classes={"bulk-action-btn"},
+                )
                 for action in bulk_action_more_list
             ],
         )

wagtail/admin/widgets/button.py

@@ -112,7 +112,7 @@ class ButtonWithDropdown(BaseDropdownMenuButton):
 
     def __init__(self, *args, **kwargs):
         self.button_classes = kwargs.pop("button_classes", set())
-        self.buttons_data = kwargs.pop("buttons_data", [])
+        self.dropdown_buttons = kwargs.pop("buttons", [])
         super().__init__(*args, **kwargs)
 
     def get_context_data(self):
@@ -120,10 +120,6 @@ class ButtonWithDropdown(BaseDropdownMenuButton):
         context["button_classes"] = self.button_classes
         return context
 
-    @cached_property
-    def dropdown_buttons(self):
-        return [Button(**button) for button in self.buttons_data]
-
 
 class ButtonWithDropdownFromHook(BaseDropdownMenuButton):
     template_name = "wagtailadmin/pages/listing/_button_with_dropdown.html"