Add rule 'no-promise-as-boolean'

[guidsdo]

This commit fixes #3983

PR checklist

• Addresses an existing issue: fixes [Rule Request] no-misused-promises #3983
• New feature, bugfix, or enhancement
  • Includes tests
• Documentation update

Overview of change:

Added rule to prevent people from using a Promise in a boolean expression.

Is there anything you'd like reviewers to focus on?

No.

CHANGELOG.md entry:

"[new-rule] no-promise-as-boolean"

[palantirtech]

Thanks for your interest in palantir/tslint, @guidsdo! Before we can accept your pull request, you need to sign our contributor license agreement - just visit https://cla.palantir.com/ and follow the instructions. Once you sign, I'll automatically update this pull request.

[guidsdo]

Build is failing due to a bug in typescript@next, please ignore this.

[JoshuaKGoldberg]

Good start!

[guidsdo]

@JoshuaKGoldberg fixed all the issues, please re-review

[guidsdo]

@JoshuaKGoldberg can I expect you to look at this before the 1st of August?

[nomcopter]

Would love to use this in tslint before it is too late!

[guidsdo]

Would love to use this in tslint before it is too late!

[JoshuaKGoldberg]

Hi folks! The 1st of August deadline is for sending PRs. I'm a bit swamped now but promise to review this, even if it's after then! 💖

[JoshuaKGoldberg]

Wonderful, thanks so much for adding this @guidsdo!

[JoshuaKGoldberg]

Ah, I don't have permissions to make the one suggested change @guidsdo. Could you please commit that suggestion and merge the latest master into this PR? Once you do, we'll be good to merge! 🚀

[guidsdo]

Ah, I don't have permissions to make the one suggested change @guidsdo. Could you please commit that suggestion and merge the latest master into this PR? Once you do, we'll be good to merge! 🚀

Thought I put that on, but thanks I applied the change and merged master into my branch :-)

[JoshuaKGoldberg]

Thanks so much @guidsdo! Rule is looking great; let's get it in.