Frontend: Various improvements / Development experience

[pierre-gilles]

So for now I’ve added 2 rules :

1. A warning for inline styles
2. An error for the @connect decorators
3. For later, add a big warning on the use of store.setState to encourage the use of local setState in components

Everything is fixed in this PR : Upgrade front Eslint, remove all @connect decorator by Pierre-Gilles · Pull Request #1766 · GladysAssistant/Gladys · GitHub