Allow dynamically set followRedirect

[VanTigranyan]

What problem are you trying to solve?

Request library allows passing followRedirect as a function that gets the intermediate response and then returns boolean, by which the library decides whether to follow the redirect. Got doesn't allow this. As a workaround, I tried to change options.followRedirect to false in beforeRedirect hook, but that doesn't work as one would expect.

Describe the feature

Allow both plain boolean and function type for the followRedirect option.
I already made proper changes in the code and in README and added tests to make sure all works correctly.
#2306
...

  const {statusCode} = await got('temporary', {followRedirect(response) {
        t.is(response.headers.location, '/redirect');
        return false;
  }});

Checklist

• I have read the documentation and made sure this feature doesn't already exist.

[sindresorhus]

Fixed by 7c3f147