[wrangler] feat: add support for placement in wrangler config

[zebp]

Allows a placement object in the wrangler config with a mode of off or smart to configure Smart placement.

What this PR solves / how to test:

Allows users to enable Smart placement via wrangler.

Author has included the following, where applicable:

• Tests
• Changeset (Changeset guidelines)

Reviewer has performed the following, where applicable:

• Checked for inclusion of relevant tests
• Checked for inclusion of a relevant changeset
• Checked for creation of associated docs updates
• Manually pulled down the changes and spot-tested

[changeset-bot]

🦋 Changeset detected

Latest commit: 97de11d

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

This PR includes changesets to release 1 package

Name	Type
wrangler	Minor

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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.devprod.cloudflare.dev/workers-sdk/runs/4885593866/npm-package-wrangler-3095

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

npm install --save-dev https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/prs/3095/npm-package-wrangler-3095

Or you can use npx with this latest build directly:

npx https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/4885593866/npm-package-wrangler-3095 dev path/to/script.js

Additional artifacts:

npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/4885593866/npm-package-cloudflare-pages-shared-3095

Note that these links will no longer work once the GitHub Actions artifact expires.

[codecov]

Codecov Report

Merging #3095 (97de11d) into main (8818f55) will increase coverage by 0.48%.
The diff coverage is 90.90%.

@@            Coverage Diff             @@
##             main    #3095      +/-   ##
==========================================
+ Coverage   74.39%   74.87%   +0.48%     
==========================================
  Files         168      179      +11     
  Lines       10585    10824     +239     
  Branches     2831     2859      +28     
==========================================
+ Hits         7875     8105     +230     
- Misses       2710     2719       +9     

Impacted Files	Coverage Δ
...ler/src/api/pages/create-worker-bundle-contents.ts	100.00% <ø> (ø)
packages/wrangler/src/dev/remote.tsx	7.73% <ø> (ø)
packages/wrangler/src/secret/index.ts	86.46% <ø> (ø)
packages/wrangler/src/worker.ts	100.00% <ø> (ø)
packages/wrangler/src/init.ts	93.56% <50.00%> (-0.26%)	⬇️
packages/wrangler/src/config/validation.ts	90.65% <100.00%> (+0.08%)	⬆️
packages/wrangler/src/create-worker-upload-form.ts	89.18% <100.00%> (+0.09%)	⬆️
packages/wrangler/src/publish/publish.ts	87.50% <100.00%> (+0.06%)	⬆️

... and 17 files with indirect coverage changes