Liquid Rust

Unfortunately, I've not had as much time to devote to this for a while. There are also a lot of weird cases that aren't too well defined or that the Ruby implementation shines through that also have me dissatisfied with Liquid. That and wanting to make it easier to extend with an embedded language. A way to solve this and my annoyance is to create a template language using an existing embedded language. I'm tempted by koto because it already has something like `|` operator (`->`) and isn't just "Rust, but embeddable" (Rust is an implementation detail; it shouldn't bleed through).

[0] https://koto.dev/

``` Performant. Do the best we can within what is conformant. ```

Would be great to have benchmarks like ops/second