Move option resolution to helpers.options

[kurkle]

• enforces consistent option fallback
• encourages consistent option naming (steppedLine = stepped or lineStepped (with type prefix))
• makes all options scriptable (most are already though)
• makes all options to be considered with 'hover' prefix in active mode
• makes all options prefixable by element type
  • borderColor -> arcBorderColor
  • hoverBorderColor -> arcHoverBorderColor
• enabled all element options to be specified in chart.options (because of spanGaps)
  • this needs to be discussed, but feels like it could make Chart.js simpler to use
• simplifies resolution customization in controller level
• makes adding new options to an element a bliss (only need to change the element)
• reduces size by 2259 bytes

this pr: 175 646 bytes
master: 177 905 bytes

downsides

• reduces control from dataset controllers (personally I do not consider this a downside)

[benmccann]

I didn't review super closely yet. I think it'll be a bit easier to take a look after rebase since a lot of the changes are already in

[kurkle]

Thanks for taking a look. I'll change this to "ready for review", when all the non related stuff is merged and rebased, so don't waste too much time on it yet :)

[etimberg]

Not sure this is the best way to go, but there are some good changes inside of this that I think are worth merging such as moving to static _defaults on the element classes.

[benmccann]

This is a pretty big one. Perhaps it could be broken into multiple PRs?

[kurkle]

#7135 is from this. I'm kind of holding back, because it seems the older ones become stale if there are many PR's.

[benmccann]

Rebase this one now that #7135 has been merged?

[kurkle]

rebased

[kurkle]

Probably not going to get merged, so I'll just close this.

[benmccann]

This function is used enough in core code that it could be helpful to add descriptions to these parameters

[benmccann]

A couple notes of things I noticed:

• I'm not sure making the dataElementType static really is much of a win because you then have to do me.constructor.dataElementType whenever you want to access it instead of me.dataElementType
• I'm not sure whether putting the options in the elements really makes sense. There are a lot of options, especially in the bar controller, like categoryPercentage that really only make sense in the context of the controller. If you put this option on a rectangle, I'm not sure that makes as much sense because it's really not specific to a rectangle. Some of the elements like point are used in multiple controllers, so putting controller options in the elements could become confusing in that case - though I don't think that's particularly an issue in the codebase it could be for custom code our users have written
• We had discussed the possibility of removing the element options. I think that might be something worth doing first. That would probably remove the duplication between the element and controller options