Allow JS Client to work with authenticated spaces 🍪

[hannahblair]

Description

This PR allows the connection to or duplication of spaces with authentication enabled. We get the cookie response from /login and if the response is ok then we parse and add the received access tokens to the the client's this.fetch function's headers.Cookie so all subsequent fetch requests will be authenticated.

Note: This won't work with EventSource as I haven't added the logic for this, since we're moving away from it anyway.

Closes: #2266

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Tests

1. PRs will only be merged if tests pass on CI. To run the tests locally, please set up your Gradio environment locally and run the tests: bash scripts/run_all_tests.sh

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[gradio-pr-bot]

🪼 branch checks and previews

•	Name	Status	URL
	Spaces	ready!	Spaces preview
	Website	failed!	Details
🦄	Changes	detected!	Details

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Install Gradio from this PR

pip install https://gradio-builds.s3.amazonaws.com/4734490e8a18c8f628c10cde888b55d0e2655ba3/gradio-4.31.3-py3-none-any.whl

Install Gradio Python Client from this PR

pip install "gradio-client @ git+https://github.com/gradio-app/gradio@4734490e8a18c8f628c10cde888b55d0e2655ba3#subdirectory=client/python"

[gradio-pr-bot]

🦄 change detected

This Pull Request includes changes to the following packages.

Package	Version
@gradio/client	minor
gradio	minor

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

With the following changelog entry.

Allow JS Client to work with authenticated spaces 🍪

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• If the bot has failed to detect any changes, or if this pull request needs to update multiple packages to different versions or requires a more comprehensive changelog entry, maintainers can update the changelog file directly.

[pngwn]

Looks great! Thanks for taking care of this @hannahblair!