[Typescript] Change all .js files into .ts(x) files

[Berhart]

This will imply:

• 1. Addition of an any type on every place that the compiler complains about
• 2. Create a global file with the entities corresponding types that come from the backend
• 3. Spread all those types across the source code

P.S: This can be done incrementally without the risk of breaking the whole app