PoC: multi-worker wrangler dev

[RamIdeas]

What this PR solves / how to test

This is a PoC for multi-worker wrangler dev.

The command now accepts multiple -c/--config args to point at multiple wrangler config file paths.

I have added a multi-worker fixture with a command in the README to run both workers in a single wrangler instance

Demo: https://www.loom.com/share/b80ac0825e3f4804ab519c2c6ca52d42?sid=75483f59-a391-4754-afc7-0732aeb9bdb7

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  • Cloudflare docs PR(s):
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[changeset-bot]

⚠️ No Changeset found

Latest commit: 7b8d728

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[penalosa]

Closing in favour of #7251