Added an optional `height` and overflow scrollbar for the Markdown Component

[ShruAgarwal]

Description

Adds an option to enable the height parameter (type: str) for a scrollable markdown. This can be used for controlling the display size of this component.

Please run demo/markdown_example to see it in action.

I kindly request you @abidlabs to please review this change and let me know your feedback! 🙂

Closes: #7455

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[gradio-pr-bot]

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Install Gradio from this PR

pip install https://gradio-builds.s3.amazonaws.com/76b87225d50105ee211814ade0222d719faef616/gradio-4.36.1-py3-none-any.whl

Install Gradio Python Client from this PR

pip install "gradio-client @ git+https://github.com/gradio-app/gradio@76b87225d50105ee211814ade0222d719faef616#subdirectory=client/python"

Install Gradio JS Client from this PR

npm install https://gradio-builds.s3.amazonaws.com/76b87225d50105ee211814ade0222d719faef616/gradio-client-1.1.1.tgz

[gradio-pr-bot]

🦄 change detected

This Pull Request includes changes to the following packages.

Package	Version
@gradio/markdown	minor
gradio	minor

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

With the following changelog entry.

Added an optional height and overflow scrollbar for the Markdown Component

Maintainers or the PR author can modify the PR title to modify this entry.

#### Something isn't right?

- Maintainers can change the version label to modify the version bump. - 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](https://github.com/ShruAgarwal/gradio/edit/scrollable-markdown/.changeset/tasty-coins-share.md).

[ShruAgarwal]

Looks great, thanks for this nice PR @ShruAgarwal! I made some tweaks for consistency with other components e.g. to make the height parameter also be able to accept an int.

Thanks a lot, @abidlabs ! 🤗😀