Add top level auto-advance toggle component.

[cjcolvar]

[masaball]

Looks good! Have a couple suggestions in the test suite, but nothing else jumped out.

[cjcolvar]

The last change I made wires the toggle up to the manifest state and the player will check that when a canvas ends playing before moving on to the next canvas. This is a fairly significant change in behavior for the player as it autoplayed by default before. We could add auto-advance behavior to all of avalon's manifests but I'm not sure how hard that would be for other adopters. Maybe we could add a prop to IIIFPlayer to opt-in to this new behavior and deprecate the old behavior to be removed in a future major release?

[cjcolvar]

There is a no-auto-advance behavior in the IIIF Presentation apec and it is supposed to be default. So I think we could consider Ramp's current behavior a bug. I'll go ahead and make the change for auto-advance to default to false unless it is present in the manifest. With this change it would probably be good to cut a major release and call out the change in behavior so adopters can modify their manifests accordingly.

[Dananji]

Looks good 💯
I had the following questions and suggestions, and one comment on the question about DRYing up the testing code above.

[Dananji]

This looks great 💯
I noticed just one thing below. After fixing it we can merge this 👍