shapes on category axis are redrawn incorrectly after zoom

[cldougl]

example: https://codepen.io/plotly/pen/79661cd85e9e51054039b89d096b0c9a

after zoom/relayout the vertical line is drawn as a rectangle or if type='line' is specified the vertical line becomes diagonal.

[etpinard]

This is a regression from 1.24.0.

Here's working example with 1.23.1:
https://codepen.io/etpinard/pen/vmqEJg?editors=0010

[etpinard]

I suspect PR #1403

[etpinard]

Ok, well this is a pretty big problem after all. Annotations, shapes and layout image on type: 'category' axes are all broken after zoom, pan or any axis-range relayout calls at the moment.

Diagnostic: in Axes.coercePosition we attempt to use ax._categories to convert string category positions to category indices. Note that, ax._categories isn't filled (nor relinked) at that point in Plots.supplyDefaults. To go around that, annotations, shapes and images defaults are called a second time during Plotly.doCalcdata if type: 'category' axes are detected. At this point ax_.categories is set, but Plots.doCalcdata isn't called on all updates (e.g. not on pan/zoom) whereas Plotly.supplyDefaults leading to bad coordinates values in fullLayout propagating to the draw methods after pan/zoom interactions.

Before PR #1403, annotations and shape used to redo their defaults in their drawOne respective methods. We could revert to doing something like that, but we can do better I think.

In component-category-axes-relayout-attempt, I propose removing logic involving ax._categories from Axes.coercePosition (as ax._categories can't be relied upon at the defaults step) and instead redefining what r (short for ranges) axes conversions methods means for category axes.

@alexcjohnson what do you think before I go any further?

[sb0007]

shapes are still broken on category axis... is this yet to be fixed?