feat: set cookie path when entering preview mode

[nicholasio]

Description of the Change

This PR improves the Next.js preview cookie handling.

First of all, it sets the preview cookie to expire within 5 minutes which aligns with the JWT token expiration.

Secondly, it will narrow the cookie to the post path being previewed so that context.preview is not true for other paths and thus avoiding bypassing getStaticProps (among other potential issues) until the cookies are cleared (either expires or the browser closes).

This would also let us eventually get rid of the requirement of having "-preview=true" in the URL.

How to test the Change

Preview a post and check if the cookies __prerender_bypass and __next_preview_data has path set to the actual path being previewed.

Alternatively, you can also test with a production build whether getStaticProps are not running for every request after previewing a post.

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.

[changeset-bot]

🦋 Changeset detected

Latest commit: 30ba50c

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

This PR includes changesets to release 3 packages

Name	Type
@headstartwp/next	Minor
@headstartwp/headstartwp	Patch
@headstartwp/core	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

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
headstarwp	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jul 11, 2023 4:16am

[github-actions]

📦 Next.js Bundle Analysis for @10up/headless_framework

This analysis was generated by the Next.js Bundle Analysis action. 🤖

This PR introduced no changes to the JavaScript bundle! 🙌

[github-actions]

📦 Next.js Bundle Analysis for @10up/headless_framework

This analysis was generated by the Next.js Bundle Analysis action. 🤖

This PR introduced no changes to the JavaScript bundle! 🙌

[github-actions]

📦 Next.js Bundle Analysis for @10up/headless_framework

This analysis was generated by the Next.js Bundle Analysis action. 🤖

This PR introduced no changes to the JavaScript bundle! 🙌

[github-actions]

📦 Next.js Bundle Analysis for @10up/headless_framework

This analysis was generated by the Next.js Bundle Analysis action. 🤖

This PR introduced no changes to the JavaScript bundle! 🙌