Linter should throw if passed a string configuration

[JoshuaKGoldberg]

Feature request

Repro

I did a silly and forgot to call JSON.parse on the value being passed to Linter.

// wrong
let linter = new Linter("file.ts", "...", "{ \"rules\": ... } ");

// correct
let linter = new Linter('file.ts", "...", { rules: ... });

Actual behavior

It ran without error, but reported 0 lint failures.

Expected behavior

It should have blown up and told me I'm an idiot for passing an invalid tslint.json equivalent.

:(

(I'll send a PR for this unless directed otherwise)

[jkillian]

Seems like a good change to make to me 👍

[JoshuaKGoldberg]

🎆