feat(member-live): sort the composite Member column by first or last name

lib/mv_web/live/member_live/index.html.heex

@@ -170,17 +170,12 @@
       <:col
         :let={member}
         :if={:name in @member_fields_visible and @compact_member}
-        sort_field={:name}
+        sort_field={if @sort_field in [:first_name, :last_name], do: @sort_field}
         label={
           ~H"""
-          <.live_component
-            module={MvWeb.Components.SortHeaderComponent}
-            id={:sort_name}
-            field={:name}
-            label={gettext("Name")}
+          <MvWeb.Components.MemberNameSortHeader.composite_name_sort_header
             sort_field={@sort_field}
             sort_order={@sort_order}
-            sort_hint={gettext("Click to sort by last name")}
           />
           """
         }