In the past, nautilus_pop_up_context_menu_at_pointer() was the common
path for popping up context menus from the view and pathbar.

However, different paths were introduced in
commit 29cf64bd and
commit 489d4d09, which
share some code but couldn't use this API.

Now that the pathbar context menus are gone, this is actually
causing more code duplication while making it harder to read.

Instead, handle everything in files-view.c.