drop vegafusion

[Jhsmit]

When using vegafusion sometimes there is an error:

thread 'tokio-runtime-worker' panicked at vegafusion-runtime\src\transform\bin.rs:43:44:
called `Option::unwrap()` on a `None` value
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Since we're precomputing binned results anyway we might want to drop vegafusion and draw filtering histogram manually from rectangles