Visualizer missing functionality and updates

[cmower]

Currently the following are missing from the visualizer

• [x] the link names should be optionally displayed
• [x] currently the user can visualize the robot links, but cannot customize their properties
• [x] move functions like https://github.com/cmower/optas/blob/17f1a1811782403af508f832216b157b24c77833/optas/visualize.py#L19-L51 into the main visualizer class, see #106
• [x] in https://github.com/cmower/optas/blob/17f1a1811782403af508f832216b157b24c77833/optas/visualize.py#L622-L654 we potentially miss out other visuals, need to iterate over urdf_link.visuals.
• [x] Add documentation to visualize.py