feat(build): add account id constant to plugins

[JGAntunes]

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Summary

Follow up to FRP-1269 - https://linear.app/netlify/issue/FRP-1269/information-request-is-the-account-id-available-for-build-plugins - after exposing the account_id within the siteInfo object from @netlify/config we still need to expose to the plugin executions. This adds ACCOUNT_ID as a undocumented constant we can use internally for now.

Validated this locally through some plugin executions that logged the constants object also:

$> node ~/workspace/netlify/build/packages/build/lib/core/bin.js --debug=true --site-id="d51b3ebf-013f-45fc-b959-b6e48c73be2d" --token=<some-token> --offline=false .


Netlify Build
────────────────────────────────────────────────────────────────
(...)
/plugin (onPreBuild event)
────────────────────────────────────────────────────────────────

{
  "CONFIG_PATH": "netlify.toml",
  "FUNCTIONS_DIST": ".netlify/functions/",
  "EDGE_FUNCTIONS_DIST": ".netlify/edge-functions-dist/",
  "CACHE_DIR": ".netlify/cache",
  "IS_LOCAL": true,
  "NETLIFY_BUILD_VERSION": "29.53.1",
  "SITE_ID": "d51b3ebf-013f-45fc-b959-b6e48c73be2d",
  "ACCOUNT_ID": "5e21500276ee6f05945b848b",
  
  (...)
  
  
$> node ~/workspace/netlify/build/packages/build/lib/core/bin.js --debug=true --account-id="i-am-an-account-id-yall" --offline=true --mode=buildbot .

Netlify Build
────────────────────────────────────────────────────────────────

(...)
/plugin (onPreBuild event)
────────────────────────────────────────────────────────────────
{
  "CONFIG_PATH": "netlify.toml",
  "FUNCTIONS_DIST": ".netlify/functions/",
  "EDGE_FUNCTIONS_DIST": ".netlify/edge-functions-dist/",
  "CACHE_DIR": ".netlify/cache",
  "IS_LOCAL": false,
  "NETLIFY_BUILD_VERSION": "29.53.1",
  "ACCOUNT_ID": "i-am-an-account-id-yall",
  "NETLIFY_API_HOST": "api.netlify.com",
  "INTERNAL_FUNCTIONS_SRC": ".netlify/functions-internal",
  "INTERNAL_EDGE_FUNCTIONS_SRC": ".netlify/edge-functions",
  "PUBLISH_DIR": "."
}

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[github-actions]

This pull request adds or modifies JavaScript (.js, .cjs, .mjs) files.
Consider converting them to TypeScript.

[JGAntunes]

This is an unrelated change I had to do to make the CI happy. All the jobs installing deps without lockfile were failing because of tsc errors:

• https://github.com/netlify/build/actions/runs/10510449486/job/29119105952?pr=5811#step:10:181