ConfiguredIdpOAuth should produce an oauth window + save JWT to storage

[tomholub]

part of #5311

[sosnovsky]

We currently don't have configured custom IdP, here we just need code skeleton to support this functionality in the future.

Mart started working on implementing custom IdP support (subtasks of #5311) and now we need to finalize remaining parts.

For testing you can configure some IdP (like https://www.okta.com) and then check that authentication process will show 2 popups - first for Gmail permissions and second one for IdP authentication (in case when user has custom AuthenticationConfiguration )

[tomholub]

Ioan, We could configure an app on Auth0 or Okta and then you could include the configuration details from the IdP in the mock api - it will get returned from the mock FES.

Then you can start the extension that uses the mock - not as a test, but for regular use. Just start the mock separately, then find the extension that was built for mock and load that into the browser.

That will let you test thoroughly.

Then for writing a test, you can configure the mock fes to send configuration that is pointing to mock idp, which we already have. Just with some slightly different parameter in the url, which will make the mock idp render slightly different ui, which you will start checking for during the test. (every time the tests go through idp ui, you'll either check that it's the mock of "normal" idp, or "custom" idp, based on what you were expecting to see)