Ensure components can be remounted with their previous data

[pngwn]

As discussed, this PR does the initial work to support only rendering the visible components. It isn't enabled in this PR because of ImageEditor related complications.

I think this will require an ImageEditor refactor, which makes more sense to take care of in the ImageEditor sprint.

So this PR is mostly an internal refactor that we can 'switch on' when the ImageEditor is in the correct shape.

[abidlabs]

Taking a look at this now @pngwn but just a thought that this might be a good time to add a demo along the lines #5217 and benchmark that demo before and after this PR, leading to some nice comms around how much faster / less memory-intensive gradio is with this PR

[abidlabs]

Very very cool @pngwn! I tried a lot of demos and generally everything is working as expected. Only two exceptions:

(1) The ImageEditor does not seem to be saving its state when unrendered and re-rendered. Try with this example:

import gradio as gr

with gr.Blocks() as demo:
    with gr.Tab("Abc"):
        gr.Textbox()
    with gr.Tab("Abc"):
        gr.ImageEditor()

demo.launch()

Screen.Recording.2024-12-16.at.3.54.09.PM.mov

I checked and on main, the ImageEditor state is saved.

(2) The webcam also seems to reset when unrendered and re-rendered. Try running demo/webcam_constraints/run.py.

Screen.Recording.2024-12-16.at.3.52.40.PM.mov

It turns out that the behavior on main is also broken but in a different way. In main, the webcam recording just becomes corrupted when a different tab is selected. The behavior I would expect is that when a different tab is selected, the webcam stops recording but the video recorded up until that point is saved.

[aliabid94]

Tried to break it with gr.render but everything worked great!

[abidlabs]

Tested a bunch of demos and everything looks good to me. Agreed let's get this out as part of ImageEditor sprint 👍