Community drawer has buttons that navigate to a view of given chats subchannels. As discussed in https://linear.app/comm/issue/DES-20/designs-for-subchannels-modal, https://linear.app/comm/issue/ENG-2373/subchannels-view this view will display items that look similar to items in SidebarListModal, so I will want to reuse a lot of the code. I extracted from code that was used to obtain chats sidebars info code that can be used to obtain chats subchannels and made wrapper functions for these two use cases.