feat(editor): Use website as the main templates repository

[MiloradFilipovic]

Summary

We are removing templates feature from the n8n app. This PR should redirect to website when /template routes are visited within the app but should preserve existing functionality for users that are using a custom templates host.

To test in-app templates repository set N8N_TEMPLATES_HOST=https://api-staging.n8n.io/api/ (some templates may not work as expected since our staging search index may not always be in sync with templates DB but the feature should work)

Related tickets and issues

Closes ADO-1789

Review / Merge checklist

• [ ] PR title and summary are descriptive. Remember, the title automatically goes into the changelog. Use (no-changelog) otherwise. (conventions)
• [ ] Docs updated or follow-up ticket created.
• [ ] Tests included.

  A bug is not considered fixed, unless a test is added to prevent it from happening again. A feature is not complete without tests.