The primary goal of the PR is to use the attachment manager from the new message composer in the LLC to manage the state of the files/image uploads and improve the overall sending flow of a message that respects the LocalMessage, Message and the sendOptions. The edit flow is also improved by relying on the LocalMessage in the PR. The LLC does the heavy lifting that we used to do in the SDK, so it's good to have a single source of truth in the SDK.

The following are the changes in the PR:

• The attachment upload now relies on the attachmentManager.uploadFiles from the message composer to attach a file.
• The preview of the upload is also handled through the attachments returned from the state of the attachment manager which means we can get rid of the imageUploads, fileUploads, setFileUploads, setimageUploads completely from the state and the context and the composer can be used for the same.
• The maxNumberOfFiles is now directly set to the composer, and the uploads are respected by checking the availableUploadSlots in the state of the attachment manager directly.
• The sendAsyncImage prop is removed, and the uploads of images through that medium are no longer supported within the SDK. This is in parity with all other SDKs, and we don't see customers using that as it was buggy, and we haven't received any bug reports for a long time. This has been decided upon based on internal discussion within the team.
• The doDocUploadRequest and the doImageUploadRequest are now unified to a single function, doFileUploadRequest, that handles all types of attachment uploads. This respects the UploadRequestFn type from the SDK.
• To handle different file upload attachment types UI, I have introduced different UI component props, including AudioAttachmentUploadPreview, FileAttachmentUploadPreview, ImageAttachmentUploadPreview, VideoAttachmentUploadPreview. This makes things a lot customizable and easier to customise. In the future, we can easily extend it to UnsuportedAttachmentPreview.
• The UploadUnsupportedIndicator is renamed to AttachmentUnsupportedIndicator as it makes more sense.
• The UploadProgressIndicator is renamed to AttachmentUploadProgressIndicator as it makes more sense.
• The DismissUpload is renamed to DismissAttachmentUpload and pretty much unified to be used everywhere in the upload previews.
• The close and reset logic of InputEditingStateHeader and InputReplyStateHeader now respects the message composer logic.
• The async audio is now sent using the attachmentManager.uploadAttachment function.
• The asyncIds, asyncUploads, imageUploads, fileUploads, setFileUploads, setimageUploads, isValidMessage, numberOfUploads, setNumberOfUploads, removeFile, removeImage, sendMessageAsync, setAsyncIds, setAsyncUploads, updateMessage, uploadNewImage, uploadFile, uploadImage are removed from the MessageInputContext henceforth. All of these can be handled using the message composer, and the flow is a lot simplified.
• The autoCompleteSuggestionsLimit, initialValue, mentionAllAppUsersEnabled and the mentionAllAppUsersQuery have been removed in favour of customizability through the middleware.
• The editMessage type is changed in the Channel component, and the MessageInputProvider calls the same with this signature:

editMessage: (params: {
    localMessage: LocalMessage;
    options?: UpdateMessageOptions;
  }) => ReturnType<StreamChat['updateMessage']>;

The sendMessage type is changed to:

sendMessage: (params: {
    localMessage: LocalMessage;
    message: StreamMessage;
    options?: SendMessageOptions;
  }) => Promise<void>;

• The theme is refactored to incorporate the new UI changes.