Major refactoring using ESLint with rules from AirBnb and Vue.
Enable most of the ESLint rules and do necessary linting in the code.
Also add more information for rules that are disabled to describe what
they are and why they are disabled.
Allow logging (`console.log`) in test files, and in development mode
(e.g. when working with `npm run serve`), but disable it when
environment is production (as pre-configured by Vue). Also add flag
(`--mode production`) in `lint:eslint` command so production linting is
executed earlier in lifecycle.
Disable rules that requires a separate work. Such as ESLint rules that
are broken in TypeScript: no-useless-constructor (eslint/eslint#14118)
and no-shadow (eslint/eslint#13014).
Implement following redirects over `fetch` supporting cookies.
`node-fetch` does not support sending cookies during redirect. However,
this is needed to not end-up in a redirect loop for a sign-in callback.
Fix integration tests failing due to redirects and 403 errors:
- Many redirects from `answers.microsoft.com` was throwing: throwing
`FetchError: maximum redirect reached` error. It was caused by not
having cookies when following redirects therefore having an infinite
sign-in callback for the webpage.
- Fixes integration tests failing due to additional referer header being
sent by the application. It adds support for making exceptions to
additional header sending through a list of regexes.
Add in-depth documentation for URL status checking.
