Add TypeScript support to ESLint.

[run1t]

It would be great to have Typescript linting available for the compiler and runtime sources.
I originally proposed to add a tslint.json file in #2895 but like @maxmilton said tslint will soon be deprecated. Even if there missing rules for typescript right know I think it can be a good idea to begin to think about this.

So I don't know what are you thought about this. But we can maybe use this issue as a place to discuss on which rules must be enforced in the source code ?