Turbo: Enable support for the View Transition API

Problem/Motivation

Turbo already supports the View Transition API and only requires both the outgoing page and income page to both have <meta name="view-transition" content="same-origin" /> so it should be straightforward to enable, allowing themes to define their own transitions.

• https://turbo.hotwired.dev/handbook/drive#view-transitions
• https://developer.mozilla.org/en-US/docs/Web/API/View_Transitions_API
• https://caniuse.com/?search=View%20Transition%20API
• https://adactio.com/journal/20195

Steps to reproduce

👀

Proposed resolution

See above.

Remaining tasks

See above.

User interface changes

Transitions easier now.

API changes

None?

Data model changes

None.