feat(authentication-oauth): callback for proxying raw request params into authentication service

[mikekolganov]

Problem: I can't get user's IP address on registration and login via OAuth.

This PR was created after this issue: #1833

Also I have related PR to feathersjs/docs#1447

Case: I have app with Facebook OAuth login flow (JWT). I need to save users IP addresses when they're registered or logged in and expected to use hooks for authentication service. Middleware for throwing raw request data to Feathers (IP address in this case) is added to middleware/index.js, assigning new keys to req.feathers object. I can see this data in context.params of all hooks except authentication service hooks (after: create()). I noticed that params are limited here and not carrying any of custom params from req.feathers object in authentication-oauth/src/express.ts

Example of use

middleware:

  app.use((req, res, next) => {
    if (! req.feathers) {
      req.feathers = {};
    }

    req.feathers.ip = req.connection.remoteAddress;
    req.feathers.userAgent = req.headers ['user-agent'];
    next();
  });

authentication config:

  app.configure(expressOauth({
    serviceParamsCallback: req => {
      const { ip, userAgent } = req.feathers;

      return { ip, userAgent };
    },
  }));

[daffl]

Thank you for the pull request. I think supporting this makes sense but couldn't we still just use req.feathers from the middleware by changing

feathers/packages/authentication-oauth/src/express.ts

Line 63 in 40b4358

const params = {

to

const params = {
  ...req.feathers,
  authStrategies: [ name ],
  authentication: accessToken ? {
    strategy: linkStrategy,
    accessToken
  } : null,
  query,
  redirect
};

[daffl]

I added a PR that implements my suggestion in #1886. I think it solves the same issue without adding an additional option.