[Tabs2] Add 'large' prop

[cmslewis]

Fixes #1506

Checklist

• Include tests
• Update documentation (automatically with new prop)

Changes proposed in this pull request:

• 💎 NEW Tabs2 now offers the large?: boolean prop to set pt-large styling via the JavaScript API.
  • ⚠️ This PR fixes a regression introduced in 1.26.0 ([Tabs] Allow nested tabs of different sizes #1476 via Prepare Release 1.26.0 #1494).
  • The deprecated Tabs component is not prohibitively affected by the regression, because consumers must supply their own <TabList> child that they can style with pt-large (small changes like this were a known risk of merging [Tabs] Allow nested tabs of different sizes #1476).

Reviewers should focus on:

• Prop description language. I took inspiration from NumericInput's large-prop description.
• Should we cut a patch release (1.26.1)?

[blueprint-bot]

Add 'large' prop to Tabs2 + tests

Preview: documentation
Coverage: core | datetime

[giladgray]

@cmslewis did you consider simply changing the CSS selector to support the old usage?

[cmslewis]

@giladgray I figured a proper JS boolean approach would be a nice-to-have over a CSS class that you have to apply explicitly (we've discussed that in the past in #992). I can try a CSS-only change if that sounds better though.

[giladgray]

I like the prop approach too, was just wondering if it was worth redoing the CSS change that caused this issue in the first place. But I'm down for what you've done here 👍

[cmslewis]

Gotcha. It's possible a CSS approach would fix the issue here, but I figure it's nice to have this JS approach available anyway, so might as well just run with this for now.