Twig Templating Block (powered by Timber) #3136

While I couldn't get the team to use Timber in favor of FSE, I've been experimenting with "Twig templating block" which allows writing custom Twig/HTML template in block editor and to map available block bindings to template context variables to supplement standard Timber post data.

It is relatively safe with unfiltered_html required, mostly equivalent to Custom HTML block with Twig auto escaping available for some extra safety.

Full Site Editor screenshot utilizing it from a site:

Example binding code & template: https://gist.github.com/jasalt/dc3d9b7704da431e184096595e0637ea

Looking to document it better during the autumn but the code is available for experimenting and it's quite succinct (~ 500LOC JS, ~ 400 LOC PHP). There's some juggling with the global state and some edge cases but has been working quite stable for usual stuff.