Upgrade @typescript-eslint/eslint-plugin to 2.0.0

[heikomat]

Version 2.0.0 of the eslint-plugin just released, with a number of interesting fixes. (see here), one of which is in regards to performance issues in certain situations that we observed aswell (see typescript-eslint/typescript-eslint#760).

Because of these performance issues, we currently supply two configs, 5minds-typescript and 5minds-typescript/fast.

We should check the changes of 2.0.0, see what we can use to improve our typescript linting, and check if the changes of typescript-eslint/typescript-eslint#760 help us identify, why 5minds-typescript is slower than 5minds-typescript/fast in monorepo-szenarios, and check if we can do something about it.