When using the preview token-exchange feature with the `openshit-v3` identity provider, a NPE is triggered, because it tries to extract the `metadata` field twice from the user profile:
```
13:17:13,667 ERROR [org.keycloak.services.error.KeycloakErrorHandler] (default task-7) Uncaught server error: java.lang.NullPointerException
at org.keycloak.broker.oidc.AbstractOAuth2IdentityProvider.getJsonProperty(AbstractOAuth2IdentityProvider.java:357)
at org.keycloak.social.openshift.OpenshiftV3IdentityProvider.extractUserContext(OpenshiftV3IdentityProvider.java:61)
at org.keycloak.social.openshift.OpenshiftV3IdentityProvider.extractIdentityFromProfile(OpenshiftV3IdentityProvider.java:87)
at org.keycloak.broker.oidc.AbstractOAuth2IdentityProvider.validateExternalTokenThroughUserInfo(AbstractOAuth2IdentityProvider.java:489)
at org.keycloak.broker.oidc.AbstractOAuth2IdentityProvider.exchangeExternalUserInfoValidationOnly(AbstractOAuth2IdentityProvider.java:548)
at org.keycloak.broker.oidc.AbstractOAuth2IdentityProvider.exchangeExternalImpl(AbstractOAuth2IdentityProvider.java:528)
at org.keycloak.broker.oidc.AbstractOAuth2IdentityProvider.exchangeExternal(AbstractOAuth2IdentityProvider.java:519)
at org.keycloak.protocol.oidc.endpoints.TokenEndpoint.exchangeExternalToken(TokenEndpoint.java:917)
at org.keycloak.protocol.oidc.endpoints.TokenEndpoint.tokenExchange(TokenEndpoint.java:696)
at org.keycloak.protocol.oidc.endpoints.TokenEndpoint.processGrantRequest(TokenEndpoint.java:194)
.....
13:17:28,916 ERROR [org.keycloak.services.error.KeycloakErrorHandler] (default task-7) Uncaught server error: java.lang.NullPointerException
at org.keycloak.broker.oidc.AbstractOAuth2IdentityProvider.getJsonProperty(AbstractOAuth2IdentityProvider.java:357)
at org.keycloak.social.openshift.OpenshiftV3IdentityProvider.extractUserContext(OpenshiftV3IdentityProvider.java:61)
at org.keycloak.social.openshift.OpenshiftV3IdentityProvider.extractIdentityFromProfile(OpenshiftV3IdentityProvider.java:87)
at org.keycloak.broker.oidc.AbstractOAuth2IdentityProvider.validateExternalTokenThroughUserInfo(AbstractOAuth2IdentityProvider.java:489)
at org.keycloak.broker.oidc.AbstractOAuth2IdentityProvider.exchangeExternalUserInfoValidationOnly(AbstractOAuth2IdentityProvider.java:548)
at org.keycloak.broker.oidc.AbstractOAuth2IdentityProvider.exchangeExternalImpl(AbstractOAuth2IdentityProvider.java:528)
at org.keycloak.broker.oidc.AbstractOAuth2IdentityProvider.exchangeExternal(AbstractOAuth2IdentityProvider.java:519)
at org.keycloak.protocol.oidc.endpoints.TokenEndpoint.exchangeExternalToken(TokenEndpoint.java:917)
at org.keycloak.protocol.oidc.endpoints.TokenEndpoint.tokenExchange(TokenEndpoint.java:696)
at org.keycloak.protocol.oidc.endpoints.TokenEndpoint.processGrantRequest(TokenEndpoint.java:194)
......
13:17:53,492 ERROR [org.keycloak.services.error.KeycloakErrorHandler] (default task-7) Uncaught server error: java.lang.NullPointerException
at org.keycloak.broker.oidc.AbstractOAuth2IdentityProvider.getJsonProperty(AbstractOAuth2IdentityProvider.java:357)
at org.keycloak.social.openshift.OpenshiftV3IdentityProvider.extractUserContext(OpenshiftV3IdentityProvider.java:61)
at org.keycloak.social.openshift.OpenshiftV3IdentityProvider.extractIdentityFromProfile(OpenshiftV3IdentityProvider.java:87)
at org.keycloak.broker.oidc.AbstractOAuth2IdentityProvider.validateExternalTokenThroughUserInfo(AbstractOAuth2IdentityProvider.java:489)
at org.keycloak.broker.oidc.AbstractOAuth2IdentityProvider.exchangeExternalUserInfoValidationOnly(AbstractOAuth2IdentityProvider.java:548)
at org.keycloak.broker.oidc.AbstractOAuth2IdentityProvider.exchangeExternalImpl(AbstractOAuth2IdentityProvider.java:528)
at org.keycloak.broker.oidc.AbstractOAuth2IdentityProvider.exchangeExternal(AbstractOAuth2IdentityProvider.java:519)
at org.keycloak.protocol.oidc.endpoints.TokenEndpoint.exchangeExternalToken(TokenEndpoint.java:917)
at org.keycloak.protocol.oidc.endpoints.TokenEndpoint.tokenExchange(TokenEndpoint.java:696)
at org.keycloak.protocol.oidc.endpoints.TokenEndpoint.processGrantRequest(TokenEndpoint.java:194)
```
* [KEYCLOAK-8575] Allow to choose between basic auth and form auth for oidc idp
* uncomment ui and add tests
* move basic auth to abstract identity provider (except for getting refresh tokens)
* removed duplications