chore: make dev state globally available

[Rich-Harris]

see #12608 (review). It's a bit annoying to have to refer to context.state.options.dev rather than just dev, but it also means that we can't use it inside functions without passing state around.

This PR puts dev in the shared state.js module, which makes everything a bit nicer. We could probably do the same thing with analysis and maybe some other things too.

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[Rich-Harris]

going to do a cheeky self-merge to unblock #12608