Add example for validating JWT in a Cloudflare Worker

[irvinebroque]

https://developers.cloudflare.com/cloudflare-one/identity/authorization-cookie/validating-json/#javascript-example is Node.js

The page links to an external 3rd party URL to guide someone using Access and Workers together: https://kinde.com/blog/engineering/verifying-jwts-in-cloudflare-workers/

Should have something first-party here, and it should guide people more clearly (esp in advance of making it easier to one-click enable Access for a Worker)

reviewing code before moving this out of draft

[github-actions]

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

Pattern	Owners
/src/content/docs/cloudflare-one/identity/	@kennyj42, @ranbel, @cloudflare/pcx-technical-writing

[github-actions]

Preview URL: https://68c94da7.preview.developers.cloudflare.com
Preview Branch URL: https://bib-workers-access.preview.developers.cloudflare.com

Files with changes (up to 15)

Original Link	Updated Link
https://developers.cloudflare.com/cloudflare-one/identity/authorization-cookie/validating-json/	https://bib-workers-access.preview.developers.cloudflare.com/cloudflare-one/identity/authorization-cookie/validating-json/

[irvinebroque]

@ranbel @kennyj42 would love a ✅ so that we have a first-party example that explains how to do this with Workers (in advance of what @stritt is cooking up to make it easier to use Workers with Access)