Support of subexpressions

[oakleaf]

Hello, it doesnt look like this repo is maintained, but if it were possible, it would be very cool to upgrade it to support PHP 8.3 (It does, but at the same time, refresh so it takes advantages of all new features).

One suggestion I am hoping for dearly is to support subexpressions, which would enable block helpers within else statements. E.g:

{{#compare "==" value1 "some"}}

{{else (compare "==" value "somethingelse")}}  <-Subexpression

{{else}}

{{/compare}}

Here's examples of how the JS lib handles it:
https://handlebarsjs.com/guide/expressions.html#subexpressions
https://handlebarsjs.com/guide/builtin-helpers.html#if