Add OidcTestClient

[sberyozkin]

The main motivation is to help Auth0 or other SaaS OIDC users to test against live test domains, where quarkus.oidc.auth-server-url is pointing to some US or EU domain. The only other options for such cases is testing with Wiremocks and unit testing with @TestSecurity. In fact this will also work for Keycloak test realms, where quarkus.oidc.auth-server-url is pointing to them, without depending on Dev Services for Keycloak.

It also fixes #30080.

After some time I've confirmed today I can write a test against the Auth0 domain which is covered in #35931.

So once this PR is ready for review and is approved, I'll update #35931.

[github-actions]

🙈 The PR is closed and the preview is expired.

[sberyozkin]

Hey @gastaldi @pedroigor Have a look please next week, this is a simple test client as an alternative to KeycloakTestClient. If we have a non-Keycloak provider, then the only option is a Wiremock based integration testing. OidcTestClient is a small utility class which expects quarkus.oidc.auth-server-url, quarkus.oidc.client-id, quarkus.oidc.credentials.secret configured - and it will discover the provided token url, and can help with password or client credential token requests against the live provider endpoint, ex, Development Auth0 tenant, etc, and then users can write tests passing these live tokens to the tested endpoint.

Will update the Auth0 tutorial afterwards

[gsmet]

I removed it from the backports as parts of it rely on other changes (it doesn't compile in 3.4). Moreover it really looks like a new feature so I think it's better to wait for 3.5.

Let me know if you think otherwise.