Cache must be cleared after changing view transitions settings

Problem/Motivation

You'll need to clear the cache for changes to view transitions settings to take effect. Is there a reasonable way to handle this automatically, or is this just too expensive (most if not all pages will probably become invalid) and something we should require a manual action for.

Also, is there any way we can make the cache invalidation less expensive here?

Steps to reproduce

Proposed resolution

Maybe a toggleable option on the settings page is a reasonable compromise?

Remaining tasks

User interface changes

API changes

Data model changes