Brushes for the graph editor

Just like there are brushes such as grab, smooth, and randomize in the object sculpting mode, there could also be brushes for the graph editor. These brushes would make it easier to adjust how smooth or randomized certain keys should be based on the brush's position, strength, and falloff. Although a grab brush can, to some extent, be imitated using the proportional editing tool, there is no easy way to imitate a smooth or randomize brush. Currently, when smoothing, all selected keys get smoothed by the same amount, and there is no brush-like falloff. And key randomization is just not an option.

Therefore, I propose adding Grab, Smooth, and Randomize brushes to the graph editor.