Centralize role preloading in global LiveView on_mount

Add ensure_user_role_loaded to global live_view quote block.
Remove redundant on_mount calls from individual LiveViews.

lib/mv_web/live/role_live/form.ex

@@ -17,8 +17,6 @@ defmodule MvWeb.RoleLive.Form do
 
   import MvWeb.RoleLive.Helpers, only: [format_error: 1]
 
-  on_mount {MvWeb.LiveHelpers, :ensure_user_role_loaded}
-
   @impl true
   def render(assigns) do
     ~H"""

lib/mv_web/live/role_live/index.ex

@@ -24,8 +24,6 @@ defmodule MvWeb.RoleLive.Index do
   import MvWeb.RoleLive.Helpers,
     only: [format_error: 1, permission_set_badge_class: 1, opts_with_actor: 3]
 
-  on_mount {MvWeb.LiveHelpers, :ensure_user_role_loaded}
-
   @impl true
   def mount(_params, _session, socket) do
     actor = socket.assigns[:current_user]

lib/mv_web/live/role_live/show.ex

@@ -19,8 +19,6 @@ defmodule MvWeb.RoleLive.Show do
   import MvWeb.RoleLive.Helpers,
     only: [format_error: 1, permission_set_badge_class: 1, opts_with_actor: 3]
 
-  on_mount {MvWeb.LiveHelpers, :ensure_user_role_loaded}
-
   @impl true
   def mount(%{"id" => id}, _session, socket) do
     try do