feat: rule @typescript-eslint/prefer-ts-expect-error

[mightyiam]

BREAKING CHANGE: add rule @typescript-eslint/prefer-ts-expect-error

https://github.com/typescript-eslint/typescript-eslint/blob/v2.29.0/packages/eslint-plugin/docs/rules/prefer-ts-expect-error.md

[LinusU]

This will make us require TypeScript 3.9 or newer, should probably document that somewhere ☺️

Actually, we should probably have a peer-dependency on typescript >= 3.9? 🤔

[toddbluhm]

This rule looks good to me. Definitely should document the typescript >= 3.9 somewhere...probably the changelog. Also as @LinusU suggested, add a peerDependency minimum version requirement.

[LinusU]

Just realised that TS 3.9 isn't released yet 😄

It's going to be released on May 12th though, which is quite soon. We could probably hold of on making another release until then? 🤔

ref: microsoft/TypeScript#37198

[LinusU]

after #287 is merged we should probably rebase this and update the version to >= 3.9 in this PR