Add TypeScript linting support

We should lint TypeScript files and try to approximate to match our ESLint configuration as close as possible.

TSLint rules we want:

• no-namespace: enforce usage of ES Modules / disallow deprecated behavior
• no-duplicate-super: prevent runtime error
• no-duplicate-switch-case
• no-duplicate-variable: prevent redeclare of var
• no-invalid-template-strings
• no-invalid-this
• triple-equals
• use-isnan
• react hooks plugin
• match eslint config closely
• restrictedGlobals

maybe:

• no-switch-case-fall-through
• no-implicit-dependencies

[christianchown]

@copiali for now, you can add linting manually:

• yarn add tslint tslint-react tslint-whatever-else-you-use
• tslint.json in your root
• "lint": "tslint -c tslint.json src/**/*.{ts,tsx}" in your package.json scripts (I also add --fix --format verbose)

and then yarn lint

[copiali]

+1 Really need support for tslint…