* PLT-5604 Add/Remove members from pubic channels doesn't match the webapp functionality
* Review feedback
* Fix spelling of ChannelMembersTitle
* Use selector to consolidate auth logic for channel member mgmt
* Fix placement of new messages separator
* Ignore your own posts when determining start of new messages
* Cache lastViewedAt in ChannelPostList until switching channels
* Increase padding around DateHeader & NewMessagesDivider
* Improve styling of new messages divider line
* Use async await for ChannelDrawerList.onSelectChannel
* Convert DateHeader to functional component
* Indicate start of new messages in posts list
* Use flag prop to indicate start of new messages in posts list
* Declare style props with View.propTypes.style
* Add icons for file types
* Compress image files for file type icons
* Add constants for file types
* Add utils for file metadata
* Add actions & reducers for fetching file attachments
* Render file attachments in posts
* Add reducers for handling files requests
* Refactor getFileType in file utils
* Refactor getFileIconPath in file utils
* Refactor getFormattedFileSize in file utils
* Trim trailing whitespace in getTruncatedFilename
* Style file attachment metadata
* Remove entity store reducer for files fetch failure
* Change filesForPost to fileIdsForPost in files store
* Use a selector for getFilesForPost
* Memoize getFilesForPost selector
* Dispatch postId with getFilesForPost
* Add test for getFilesForPost
* Upload seed file in getFilesForPost test
* Display correct icon for image attachments
* Fix reducers for receiving files for post
Expect response data to be array not object
* Style attachment post
* Merge headers (defaults + opts) in Client.doFetch
* Upload file as FormData
* Use form-data lib instead of built-in polyfill
* Associate file with post in getFilesForPost test
* Improve assertions in getFilesForPost test
* Check for createPost failure in getFilesForPost test
* Use correct post id in getFilesForPost test
* Use client not action to create post in getFilesForPost test
* Fix file upload in getFilesForPost test
* Add assertion for name of uploaded file
* Update attachment post style
* Fix spelling of loadFilesForPostIfNecessary
* Remove eslint-disable no-magic-numbers from file_utils.js
* Remove unused index prop from FileAttachment
* Clarify code for merging headers in Client.getOptions
* Dynamically truncate file attachment names
* Extract component for FileAttachmentIcon
* Use white bg for FileAttachmentIcon to match webapp styles
* Match webapp styles for file attachment borders
* Move file icon path lookup to FileAttachmentIcon
* Use more logical ordering for file type lookup
