Add Features to send Files/Images via messages

[Hadeso-0]

Implement the functions to send files in messages.

How to approach

1. When a user adds a file, the UI must store it in some Array<File>.
2. User can add multiple files and edit the File Array via a cross button on the top-right corner of the file thumbnail.
3. When the user clicks send, the client app must upload each file to the cloud storage (Firebase storage in this case), and send a new chat with __type = type of file [ to appropriately render it on the app ] and content = LINK OF THE UPLOADED DOCUMENT.

Todo-

• Upload Images/ videos #2
• Upload Documents/ files #4
• Upload Contact Card #3