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. Therefore I had to change some names, so that they don't suggest the types / functions can only be used for sidebars.
`sidebarInfoSelector` can be reused almost entirely for fetching subchannels info. The only difference is that from all children of a chat, that we get from `childThreadInfos`, we don't want to omit the ones that are not sidebars (or sidebars the user doesn't belong to), but the ones that are sidebars - since all other children are valid subchannels. For this reason `threadInfosWithLastUpdatedTimeAndNonLocalMessageSelector` function was created - it takes the contition that filters out the threads we don't want to display, and returns a selector that uses this condition.