Blueprint: Rename isDisabled to disabled

[llorca]

There's still a few instances of isDisabled here and there

[cmslewis]

Remnants of a golden era. I'm going to miss those helping-verb prefixes.

[adidahiya]

+1 to @cmslewis; I also like the helping-verb prefixes. I guess the idea here is that we are mimicking the behavior of the HTML disabled attribute so we're trying to be consistent? I could see this going either way, but would get a little worried if we removed _all_ such prefixes from prop names ("should", "use", etc.)

[llorca]

What's important is staying consistent. This task is about choosing between isDisabled or disabled and sticking with it, but if you think there's a larger "do we use verb prefixes" task to look at, happy to file.

[leebyp]

Slightly tangential but I wonder if we should just remove disabled altogether in some of these components in question; I'm thinking <Button />, <InputGroup /> and explicity say that we're proxying HTML props through to the underlying HTML.

[giladgray]

we _do_ spread HTML props, but disabled exists in the interface precisely so it appears in the documentation. this came up recently in #396 where someone didn't realize that it was supported.

[llorca]

I just saw references to isActive, does this issue also apply to it?

[cmslewis]

@llorca take a look. Are we done with the isDisabled => disabled transition? Only a few search results left, none of them props:

https://github.com/palantir/blueprint/search?utf8=%E2%9C%93&q=isDisabled&type=

[llorca]

looks done indeed