Improve linting & prettier settings

[danielpeintner]

Note: coming from #7 (comment)

I noticed some shortcoming w.r.t. to the current setup.

• in node-wot we used to have eslint-plugin-unused-imports. I think having this might be useful
• I also noticed that "npm run lint" does not screem if I have unused variables in my code. Useful again I think.
• I also wonder whether prettier & linting should be based on language level (hence moving it into the /node directory )

[egekorkan]

I also wonder whether prettier & linting should be based on language level (hence moving it into the /node directory )

I agree with this one.

For the other two, I am fine with aligning with node-wot here.