Fix: Avoid unnecessary rebuilding pages functions in wrangler pages dev

[Maximo-Guk]

Fixes #3258.

Avoid unnecessary rebuilding pages functions in wrangler pages dev

This was happening as we were using esbuild's watching mechanism + our own custom watcher which was causing high cpu usage and duplicate rebuilds on any file changes.

We have our own custom watcher setup in dev mode so that we can watch for new files that are added, as esbuild's watcher doesn't catch this

Author has included the following, where applicable:

• Changeset (Changeset guidelines)

Reviewer is to perform the following, as 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: f4052fc

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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[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/5047188012/npm-package-wrangler-3311

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

npm install --save-dev https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/prs/3311/npm-package-wrangler-3311

Or you can use npx with this latest build directly:

npx https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/5047188012/npm-package-wrangler-3311 dev path/to/script.js

Additional artifacts:

npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/5047188012/npm-package-cloudflare-pages-shared-3311

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

[codecov]

Codecov Report

Merging #3311 (f4052fc) into main (99e6ccf) will increase coverage by 0.09%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #3311      +/-   ##
==========================================
+ Coverage   75.44%   75.54%   +0.09%     
==========================================
  Files         180      180              
  Lines       11003    10982      -21     
  Branches     2887     2885       -2     
==========================================
- Hits         8301     8296       -5     
+ Misses       2702     2686      -16     

Impacted Files	Coverage Δ
packages/wrangler/src/pages/build.ts	68.08% <ø> (ø)
packages/wrangler/src/pages/dev.ts	17.47% <ø> (ø)

... and 5 files with indirect coverage changes