Linter: enforce quotes for JS object attributes

[ikalnytskyi]

Rationale

So far we have weird ESLint setup as it requires to do not use quotes for plain attribute names, and enforce quotes for complex ones. I.e. the resulting code looks like:

{
  Accept: 'application/json',
  'Content-Type': 'application/json',
},

It'd be much better if won't mix those styles and use only possible style which is "quotes" since it covers all cases.

Solution

Adjust ESLint rules and fix the code.