Add a button to show/hide the axis indicator

[toloudis]

Use Case

volume-viewer supports hiding/showing an axis indicator in the corner of the display. But there is no control for it in the react front end.

Solution

Add a button in the top set of controls before the Channels, on a new row

Acceptance criteria

A button that toggles the axis indicators on the 3d canvas. Button should say "Show Axes" when the axes are NOT visible, and "Hide Axes" when the axes ARE visible.

[toloudis]

I thought of one addition to this that I forgot to specify, which will probably be nice to have. We would like to allow the viewer to be initialized with axes on or off, so:

• add a prop to the main app component with a boolean value so we can have it initialize to on or off.
• you can test the prop in the public/index.jsx app by just hardcoding its value to true or false.
• the prop should be a child of the already existing viewerConfig prop

[frasercl]

Resolved by #29