Npm linting

[brettz9]

What is the purpose of this pull request?

• Documentation update
• Bug fix
• New rule
• Changes an existing rule
• Add autofixing to a rule
• Other, please explain: Chores (though package.json properties also useful on npmjs.com)

What changes did you make? (Give an overview)

Builds on #183. This now builds on #191 . This now builds on #195

• Linting: As per latest prettier
• npm: Update prettier-related devDeps.
• Testing: Fix test expectation broken on master

[brettz9]

I've changed this as discussed in #185 . Now builds on #191 (which adds non-prettier npm changes) and this now just adds the following on top:

• Linting: As per latest prettier
• npm: Update prettier-related devDeps.

[brettz9]

Note that in this PR, besides the stylistic changes, I added one message to an invalid test in __tests__/prefer-await-to-then.js as it should now expect three errors, not two (i.e., report the catch also as per the changes in 6378bb9 ).

That is the reason this is based on master instead of development, because development hasn't yet merged the master changes, but it is necessary to fix that test in master regardless.

[brettz9]

Because of the need to fix the issue just mentioned which I've already filed in #195, I've rebased this PR on top of #195. I therefore think you'll want to review that one first, as your master is broken without it. Thanks!