Fix CrossOriginWorkerMaker to cache the blob URL

[whitphx]

Description

There is a bug that multiple SharedWorker-s are created for the same site when the Lite's worker script (webworker.js) is loaded from a different origin through CrossOriginWorkerMaker.
It is because this part is called every time a new worker is created.
To avoid it, caching mechanism is introduced in this PR.

[gradio-pr-bot]

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Install Gradio from this PR

pip install https://gradio-builds.s3.amazonaws.com/4b090da8b8ccd982cc4bd95efb443a1e44848509/gradio-4.20.1-py3-none-any.whl

Install Gradio Python Client from this PR

pip install "gradio-client @ git+https://github.com/gradio-app/gradio@4b090da8b8ccd982cc4bd95efb443a1e44848509#subdirectory=client/python"

[gradio-pr-bot]

🦄 change detected

This Pull Request includes changes to the following packages.

Package	Version
@gradio/wasm	minor
gradio	minor

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With the following changelog entry.

Fix CrossOriginWorkerMaker to cache the blob URL

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[aliabd]

@whitphx the changes look good, but how should I test this?

[whitphx]

@aliabd
The points are

• Serve the Lite scripts and a web site from different origins.
• Run multiple Lite apps in a browser.
• Confirm only one SharedWorker is created.

For example,

1. Build Lite and serve the scripts from one port of localhost, e.g. from localhost:8000.
2. Import the served script (http://localhost:8000/path/to/lite.js) from another website (e.g. js/_website) and embed a Lite app enabling the SharedWorker mode.
3. Serve the website from a different port e.g. localhost:5173.
4. Open the website e.g. http://localhost:5173/path/to/page in Chrome in multiple tabs, and confirm the Lite app is working.
5. Open chrome://inspect/#workers and confirm only one SharedWorker is created.

[pngwn]

Looks great and seem to work well as far as I can test! Thanks @whitphx!

Could we change these functions and variables to use snake_case like the rest of the library?

[whitphx]

@pngwn Updated 👍

[pngwn]

Awesome. Thanks again @whitphx!

[abidlabs]

I'll go ahead and merge this in to get it out for the release.

cc @aliabd as well for visibility