Add $schema to Wrangler jsonc config

[WalshyDev]

Summary

When rendering Wrangler config, it's commonly provided in TOML. When we do this, we convert it to JSON to render as an option. That's great but in TOML we don't specify a schema but on JSONC we want to. So, add the $schema at the top with the expected value.

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[github-actions]

This pull request requires reviews from CODEOWNERS as it changes files that match the following patterns:

Pattern	Owners
*.astro	@cloudflare/pcx-content-engineering, @kodster28

[github-actions]

Preview URL: https://7361e5c5.preview.developers.cloudflare.com
Preview Branch URL: https://walshy-add-schema.preview.developers.cloudflare.com