scattergl: make selection's eventData the same as in scatter traces

[antoinerg]

This PR makes scattergl traces return selection's eventData that's the same as in scatter.

Closes #5533

[archmoj]

Looks great!
@antoinerg are you going to test scatterpolar and scatterpolargl as well?

[antoinerg]

Looks great!
@antoinerg are you going to test scatterpolar and scatterpolargl as well?

I didn't realize we also had categorical axes on scatterpolar plots 😮 . Yes, let me check those out!

[antoinerg]

In 4fd7070, I added a test to check that scatterpolargl and scatterpolar produce the same eventData.

I should mention that in both scatter and scatterpolar, the test coverage is not 100% as I only run the tests on one axis instead of both of them. Let me know if you want me to test both axes. The tests now 🔒 down the behavior on both axes for both scattergl and scatterpolargl.

[archmoj]

Nicely done.
💃

[nicolaskruchten]

Phew, good timing on this find and fix, right before 2.0 :)