Fix Model3D download button and other issues

[freddyaboulton]

Description

Closes: #6325

Also fixes some more issues with Model3D

• The upload event was not triggering
• The clear event was not triggering a change event

Added an e2e test for this too!

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Tests

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[gradio-pr-bot]

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Install Gradio from this PR

pip install https://gradio-builds.s3.amazonaws.com/957bdb69c487b06c3007feeba7753f3b68c0f478/gradio-4.2.0-py3-none-any.whl

Install Gradio Python Client from this PR

pip install "gradio-client @ git+https://github.com/gradio-app/gradio@957bdb69c487b06c3007feeba7753f3b68c0f478#subdirectory=client/python"

[gradio-pr-bot]

🦄 change detected

This Pull Request includes changes to the following packages.

Package	Version
@gradio/model3d	patch
gradio	patch

• Maintainers can select this checkbox to manually select packages to update.

With the following changelog entry.

Fix Model3D download button and other issues

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[abidlabs]

LGTM! Thanks for adding the e2e test @freddyaboulton

[abidlabs]

Merging so that we can get it out for the release!