Add config options in plot schema

[etpinard]

resolves #2703

Unlike #1188, this PR doesn't try to make the config options (or attributes?) compatible with Lib.coerce. Instead, this PR just lists valType and description fields for all the config options and formats them into the schema. Here, the default config "object" stays the same, hence there's no breakage in the behaviour.

Go to https://22282-45646037-gh.circle-artifacts.com/0/plot-schema.json and <ctrl-f> for "config": to see the results.

cc @plotly/plotly_js

[etpinard]

... @archmoj would you mind taking a look at this one at some point this week?

[archmoj]

This one is also interesting to review. Thanks @etpinard.

[archmoj]

Great PR.
I was wondering it may be useful for the users to have the plotly.js version written in the plot-schema.json.
Thanks @etpinard.

[archmoj]

It may be useful to have a max for this.

[etpinard]

Currently the Queue logic has no limit to the number of items.

You're right though, there should probably be a max, but as this is deprecated code, I'll pass.

[archmoj]

We may apply the changes to this attribute from other PR #3422:

plotly.js/src/plot_api/plot_config.js

Lines 147 to 159 in 16a01e7

	scrollZoom: {
	valType: 'flaglist',
	flags: ['cartesian', 'gl3d', 'geo', 'mapbox'],
	extras: [true, false],
	dflt: 'gl3d+geo+mapbox',
	description: [
	'Determines whether mouse wheel or two-finger scroll zooms is enable.',
	'Turned on by default for gl3d, geo and mapbox subplots',
	'(as these subplot types do not have zoombox via pan),',
	'but turned off by default for cartesian subplots.',
	'Set `scrollZoom` to *false* to disable scrolling for all subplots.'
	].join(' ')
	},

[etpinard]

Yes, I'm planning on merging #3422 into this PR.

[etpinard]

got a in-person 💃 from @archmoj - merging!