Make all ticks objects

[benmccann]

Closes #5019

There's a ton of tests that will need to be updated to expect tick objects instead of strings, but otherwise this is mostly working. I wanted to get some feedback before I finish that

A couple things that could be cleaned up:

• There's a few places that could be less code if we could use es6, but the linter won't let us yet. Allow using es6 syntax for Chart.js 3.x eslint-config-chartjs#1
• convertTicksToLabels would probably be less code if it modified ticks in place to set the labels rather than returning the labels and then having core.scale put the labels on the ticks

[kurkle]

Couple of suggestions, but I'm good with this implementation too.
This is a good cleanup!

[etimberg]

I like the direction this is going. I agree with @kurkle's points above. Updating to generateTickLabels will also make the interface clearer I think

[kurkle]

I think you can go ahead and fix the tests.

[benmccann]

Ok. All tests should be passing now

[etimberg]

I didn't have any complaints.

[etimberg]

shall we merge this?

[benmccann]

I'm ready if you both are