Setting up basic GUI

I made a mistake in my initial plan for this project. I wanted to get all the data loading parts done first as I have done json handling in other languages. This would have worked were I familiar with flutter. However, as I am still very new to flutter, I have been spending time trying to figure out how to process the data so it can easily be converted to flutter GUI; I am not sure what tools I have available as I just don’t have a lot of experience. Therefore, I decided I need to work on the UI along with the data processing. I created an app bar that moves the upload button onto it with an IconButton, and I am using the resizable_widget library to create the three panel structure of Google Chat.