Better image support

[josevalim]

There are some ideas flying around:

1. [x] Support Nx.Tensor in Kino.Image by using a custom content type that is loaded into a canvas
2. [ ] Have a canvas input
3. [x] Have a camera input
4. [x] Have a specific image tensor upload, where the image is loaded into a canvas to be converted into pixels (and potentially resized)

[cocoa-xu]

Hi @josevalim, I'd like to add support for camera input if currently no one is working on it. :)

[josevalim]

Yes, please go ahead. Let’s start with camera image first, so there is an explicit click button to take a picture?

[cocoa-xu]

Yeah, I'm thinking something like this:

And, of course, we can probably also make it optional here, something like Kino.Input.image("Image", camera: false).

Linked PR: https://github.com/livebook-dev/livebook/pull/1595