Add Viser buttons to RRT example

[sea-bass]

Instead of the RRT Example just picking a random start/goal pose and planning once, we should add Viser buttons to the example.

This could be for:

• Randomizing poses and planning
• Executing a planned path
• Enabling/disabling path shortcutting

Additionally, it would be good to ease up on the printing of full paths/trajectories, and instead print how long it took to plan/shortcut/time trajectories.