Setup automated publishing

[emmatown]

This uses https://github.com/changesets/action in a slightly weird way now.

We still use the Action to create the PR(and not publish) and that's unchanged.

Now there's a new workflow that also runs the Changesets Action but:

• it's assumed it will only run when there are no changesets so it only does publishing
• it's triggered by a workflow dispatch
• it requires approval to allow the npm token to be used (this is separate to the workflow dispatch)

(re why use the action and not just run changeset publish: I didn't want to worry about how to get npm authenticated, getting git authenticated with the right credentials and pushing tags so I just used the action since I know It'll Work)

[changeset-bot[bot]]

⚠️ No Changeset found

Latest commit: 595aa7c640af5448840a2c75e8fea87f4ad764a6

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