Preview tokens 5: Version-based rendering

[lukasbestle]

🚨 Merge first

• Preview tokens 1: Groundwork A (Testing) #6821
• Preview tokens 2: Groundwork B (Core) #6822
• Preview tokens 3: Preview URL refactoring #6823
• Preview tokens 4: VersionId::render() #6824

Description

Summary of changes

$page->render() is now responsible to choose the correct version to render.

Users can at any time pass a custom version ID that will always be used if passed. Otherwise the version ID is auto-detected.

If a render version is already set globally, this is the first detection priority. This can be relevant if a template calls $somePage->render() of another page. By using the global render version ID, that rendered version will match the one of the "outer" page.

Otherwise the version ID will be taken from the request. In this PR this only re-implements the draft tokens.

Reasoning

• Usage flexibility
• DRY code

Additional context

• Logic is moved over 1:1 for now. Following PRs 7-9 will implement the actual version tokens.
• Tests need to disable caching in this PR because the current caching logic would make those tests fail otherwise. PR 6 will fix this and delete the temporary TODO additions to the tests.

Changelog

Enhancements

• It is now possible to override the version ID in $page->render() with the new $versionId parameter.

Refactoring (since alphas)

• Move request-based version detection from the App class closer to the action in $page->render()

Docs

We could document the new $versionId argument to $page->render(). But I don't think we already have a place in the guide or cookbook that uses $page->render(), at least I couldn't find one.

Ready?

• In-code documentation (wherever needed)
• Unit tests for fixed bug/feature
• Tests and CI checks all pass

For review team

• Add lab and/or sandbox examples (wherever helpful)
• Add changes & docs to release notes draft in Notion

[bastianallgeier]

It all looks very clean to me. But a second pair of eyes from @distantnative would be good :)

[bastianallgeier]

We mention the render method in the routing guide: https://getkirby.com/docs/guide/routing I'm not really sure if it actually fits there to document the $versionId argument.

But we should definitely add an example here: https://getkirby.com/docs/reference/objects/cms/page/render