[Table] Create a playground where you can toggle all features in one place

[cmslewis]

Changes proposed in this pull request:

• Out with the old perf.html spreadsheet example.
• In with the new Table Playground. (The term "playground" is a little overloaded now; feel free to suggest something else, though note that string doesn't appear in this PR.)

Reviewers should focus on:

• I've discovered so many Table bugs and/or weirdnesses from this already!
• I want to merge this quickly and add to it iteratively in future PRs (TODO: text truncation, resizeByTallest..., reorganize the table preview pages).
• Play with it at [table docs url]/perf.html.
• Happy to polish styles in future PRs if we need to.

Screenshot

[cmslewis]

Time to improve the build setup for this preview page methinks (future PR).

[cmslewis]

tbl- is my little custom namespace.

[cmslewis]

Happy to do this in this PR. Wasn't able to wrangle it after a few seconds of poking, so I copied+pasted to unblock myself.

[blueprint-bot]

Better styles

Preview: documentation | table
Coverage: core | datetime

[adidahiya]

• unchecking "multiple selections" disables drag-to-select-a-region. not sure if this is intentional
• unchecking "focus cell" disables the feature but keeps around the old focussed cell

overall looks good! can we throw in a focus style manager "only show outline on tabs" somewhere?

[tgreenwatts]

Insert with random text takes a shockingly long time, but other than that looks great! Excited to use this going forward

[tgreenwatts]

The focus cell doesn't move around :(

[cmslewis]

@adidahiya:

1. According to the current implementation, "multiple" = more than one thing. "drag-selection" = more than one cell, hence Table disables it. i don't necessarily agree with this logic though; intuitively, i'd expect allowMultipleSelections={false} to simply disable cmd + select another region.
2. That's due to an issue with componentWillReceiveProps in Table, not in the example code.

@tgreenwatts:

1. Fill with random text seems super screwy right now in general. Was already like this though.
2. Was aware of the broken focus-cell hotkeys. Can fix later.

[blueprint-bot]

Focus style control

Preview: documentation | table
Coverage: core | datetime

[cmslewis]

@adidahiya I added a focus-style control.

[blueprint-bot]

Sync focus style on componentDidMount too

Preview: documentation | table
Coverage: core | datetime

[cmslewis]

Merging because this only affects internal Table preview, and I have other stuff I want to do with it today.