normalise install + build flow across CI

[pngwn]

• I have searched to see if a similar issue already exists.

A few issues:

Wheel creation

We create build artifacts slightly differently across different parts of our CI:

In PRs we create the gradio wheel as part of the deploy-spaces workflow but when releasing we do this directly in the publish workflow (the work is actually delegated to an action).

@gradio/lite

We do not generated a wheel for @gradio/lite nor do we create previews. We should do both of these things.

Access to dist files

The gradio dist files are technically accessible via the s3 bucket but we don't make it particularly easy to get hold of them (for debugging purposes).

We should add download links to the install comment, for debugging purposes. We should do the same for @gradio/lite (when we have aded the wheel build).

[freddyaboulton]

I also think we may be re-using the cache incorrectly. This run failed because ruff was not in the cache and so the latest version of ruff got installed and the lint failed.

https://github.com/gradio-app/gradio/actions/runs/8455401241/job/23162803394

I think this happened because a previous cache got deleted when we were debugging the lite build and lite does not install ruff. Maybe it's a corner case but flagging here jic.