PR - TypeScript Conversion

I set for myself the goal to make a "mini" app project, in order to showcase my skills and thought about what the basic functionality of backend server required, so that I can execute async calls from my client code, and add records in a db, so I saw the work that you did and think it's really quite well thought through, but I also want to demonstrate my typescript abilities.
I wanted to use your work for a basis and did a complete typescript overhaul of all src and tests js files. All existing package.json scripts are running as before with noted changes (I will point these out in a pr).

Scope of changes:

Code:
All function parameters and return types defined (where practical)
Best effort to keep the original function signtatures unchanged.

Build-Configuration:
Due to inclusion of TypeScript, have modified executable dev dependencies 'ts-node' for 'dev' script, babel-jest for 'test' script and 'babel-ci' for the 'server' script transpilation to 'dist' out directory.

Eslint:
Have replaced extends "airbnb-base" with "airbnb-typescript" (and other typescript contraints).

Docker:
Reordered DockerFile 'USER node' to first execution position and creating the checkout working directory /home/user/nope-app.