Display a more helpful error when publishing to a route in use by another worker

[caass]

Display a more helpful error when trying to publish to a route in use by another worker.

Previously, when trying to publish a worker to a route that was in use by another worker,
there would be a really unhelpful message about a failed API call. Now, there's a much
nicer message that tells you what worker is running on that route, and gives you a link
to the workers overview page so you can unassign it if you want.

 ⛅️ wrangler 2.1.11
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Total Upload: 0.20 KiB / gzip: 0.17 KiB

✘ [ERROR] Can't publish a worker to routes that are assigned to another worker.

  "test-custom-routes-redeploy" is already assigned to route
  test-custom-worker.swag.lgbt

  Unassign other workers from the routes you want to publish to, and then try again.
  Visit
  https://dash.cloudflare.com/<account_id>/workers/overview
  to unassign a worker from a route.

Closes #1849

[changeset-bot]

🦋 Changeset detected

Latest commit: e1a0eda

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
wrangler	Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

A wrangler prerelease is available for testing. You can install this latest build in your project with:

npm install --save-dev https://prerelease-registry.developers.workers.dev/runs/3249591395/npm-package-wrangler-2023

You can reference the automatically updated head of this PR with:

npm install --save-dev https://prerelease-registry.developers.workers.dev/prs/2023/npm-package-wrangler-2023

Or you can use npx with this latest build directly:

npx https://prerelease-registry.developers.workers.dev/runs/3249591395/npm-package-wrangler-2023 dev path/to/script.js

Additional artifacts:

npm install https://prerelease-registry.developers.workers.dev/runs/3249591395/npm-package-cloudflare-pages-shared-2023

[codecov]

Codecov Report

Merging #2023 (e1a0eda) into main (932fecc) will decrease coverage by 0.16%.
The diff coverage is 12.50%.

@@            Coverage Diff             @@
##             main    #2023      +/-   ##
==========================================
- Coverage   72.77%   72.61%   -0.17%     
==========================================
  Files         122      122              
  Lines        8368     8392      +24     
  Branches     2197     2203       +6     
==========================================
+ Hits         6090     6094       +4     
- Misses       2278     2298      +20     

Impacted Files	Coverage Δ
packages/wrangler/src/publish/publish.ts	85.71% <12.50%> (-5.90%)	⬇️
...ackages/wrangler/src/__tests__/helpers/mock-bin.ts	100.00% <0.00%> (+5.26%)	⬆️

[penalosa]

Couple comments, but looks good!