THREESCALE-15279: Add an "audience" protocol mapper to Keycloak integration

[jlledom]

Jira Issue:

https://redhat.atlassian.net/browse/THREESCALE-15279

Description:

As the issue describes, after a breaking change in a recent RHBK release, the token introspection feature stopped working. In order to fix it, we need to ensure the access token received from keycloak includes the client id in the aud field.

Keycloak provides a way to write on this field, which is installing a protocol mapper type oidc-audiende-mapper in all clients.

This PR modifies the Keycloak integration in Zync to add such mapper in the requests to the client registration service in Keycloak.

Verification steps:

1. Ensure the server allows the oidc-audience-mapper for client registration
   • Keycloak: Realm Settings -> Client Registration -> Client Registration Policies
   • RHBK: Clients -> Client Registration
   • In both cases, add oidc-audience-mapper to the Allowed Protocol Mapper Types policy for both Anonymous and Authenticated clients
2. Sync an application from porta. The fastest way is to regenerate the client secret.
3. You should see the mapper in the server UI
   • Keycloak: Clients -> [client id] -> Mappers
   • RHBK: Clients -> [client id] -> Client Scopes -> [client id]-dedicated -> Mappers
4. Get an access token

ACCESS_TOKEN=`curl   -d "client_id=[client_id]"   -d "client_secret=[client_secret]"   -d "grant_type=client_credentials"   "[endpoint]/auth/realms/[realm]/protocol/openid-connect/token" | jq -r '.access_token'`

5. Get the introspection token

curl -X POST     [endpoint]/auth/realms/joan/protocol/openid-connect/token/introspect     -u "[client_id]:[client_secret]"     -d "token=$ACCESS_TOKEN"

6. You should get a valid token. If you get {"active": false} then it's not working.