Add FreeverbNode

[CorvusPrudens]

This PR introduces a simple reverb node using the freeverb algorithm.

The implementation I pulled this from uses f64s internally, but we could swap them out for f32, likely without any real loss in quality.

The processor has proper smoothing for its parameters, performs declicking when paused, and does a crude silence analysis when its inputs are silent. It appeared to be working correctly in my testing, but I haven't done a full test with the code in Firewheel. I'll report back when I've finished that testing.

[CorvusPrudens]

Okay, I've tested the node in context, and after the updates it continues to work as expected.

I did make some changes to the Notify implementations. They received some optimizations that, while avoiding allocations, also dropped the notify counter. This caused false positives for change detection and messed with sampler completion detection. I provided alternative, moderate optimizations for smaller types, and simply reverted to allocations for larger ones. Let me know if this seems reasonable.