Create parameter groups and "important" parameters in `nightgraph-ui`

[kneitinger]

When using many parameters in a sketch, the UI's parameter tab can get a bit cluttered. To relieve this,

it would be nice to allow parameters to be grouped, for example the parameters for a sine wave being next to each other and padded from others with a separator...or even all of them being in an egui CollapsingHeader

Even easier, it would be helpful to allow parameters to be tagged as important (or some similar and shorter word) and appear in the parameter panel as bold text

#[param(default = 3, important)]
sine_wave_count: u32