feat: add support for vercel visual editing

[mwickett]

🎟️ Asana Task

---

Description

This adds necessary headers to our graphql requests to DatoCMS to enable the visual editing feature (Vercel Docs / Dato Docs)

This is similar to https://github.com/hashicorp/web/pull/455/files

Note: before this merges (really before the version is bumped on consuming projects), each Vercel project that uses Dato will need to have a HASHI_DATO_PROJECT env variable added with the slug of the Dato URL. For us, possible values include:

• hashicorp
• io-marketing-sites
• hashiconf
• hashidays
• internal-www
• how-hashicorp-works

PR Checklist 🚀

• Conduct thorough self-review.
• Add or update tests as appropriate.
• Write a useful description (above) to give reviewers appropriate context.
• Identify (in the description above) and document (add Asana tasks on this board) any technical debt that you're aware of, but are not addressing as part of this PR.

[changeset-bot]

🦋 Changeset detected

Latest commit: 79ade70

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@hashicorp/platform-cms	Minor
@hashicorp/platform-cli	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

📦 Canary Packages Published

Latest commit: 79ade70

Published 2 packages

@hashicorp/platform-cli@2.7.3-canary-2023513203633

npm install @hashicorp/platform-cli@canary

@hashicorp/platform-cms@0.5.0-canary-2023513203633

npm install @hashicorp/platform-cms@canary