Attach elem_classes selectors to layout elements, and an id to the Tab button (for targeting via CSS/JS)

[abidlabs]

This PR does two things:

1. It passes the elem_classes attribute to the Blocks layouts (e.g. Row, Accordion, Tab, etc.) We had these attributes set up correctly in the frontend, but we were never passing them in from the frontend

2. For the TabItem, the elem_id would get attached to the div holding the tab contents. We now also attach an {elem_id}-button to the button that you click on to select the tab. This closes: Add id, class, and or attribute to a Tab's button #5585

Test code:

import gradio as gr

css = """
#blue-button{
    background-color:aqua
}
#green-button {
    background-color:green
}
#red{
    background-color:red
}
"""

with gr.Blocks(css=css) as demo:
    with gr.Tab(
            "Blue",
            elem_id="blue",
        ):
            gr.Textbox()
    with gr.Tab(
            "Green",
            elem_id="green",
        ):
            with gr.Accordion("Red background", elem_id="red"):
                gr.Textbox()
                gr.Textbox()
        
    demo.launch()

[gradio-pr-bot]

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---

Install Gradio from this PR

pip install https://gradio-builds.s3.amazonaws.com/bae6a1ebcbd832f00c2b2b47cd22a28e5be89683/gradio-3.44.4-py3-none-any.whl

Install Gradio Python Client from this PR

pip install "gradio-client @ git+https://github.com/gradio-app/gradio@bae6a1ebcbd832f00c2b2b47cd22a28e5be89683#subdirectory=client/python"

[gradio-pr-bot]

🦄 change detected

This Pull Request includes changes to the following packages.

Package	Version
@gradio/tabitem	patch
@gradio/tabs	patch
gradio	patch

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Attach elem_classes selectors to layout elements, and an id to the Tab button (for targeting via CSS/JS)

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[pngwn]

In Svelte if you set an attribute to null it gets removed. That might be a slightly cleaner way of expressing this.

[abidlabs]

Ah nice. Figured there'd a nicer way. Will update

[dawoodkhan82]

Nice! just tested and everything looks good.

Small nit: wondering if we should name the tab button {elem_id}-tab-button to be more specific.

[abidlabs]

Thanks @dawoodkhan82 for reviewing!

I don't think we need to be more specific, users can select by tab-nav>{elem-id}-button if there's a different element with the {elem-id}-button ID somewhere on the page.