[AEROGEAR-7556] Reconcile Keycloak clients

[vchepeli]

Description

• Clients are initially created in the reconcileRealms() function, as declared in the keycloak.json
• Clients that are updated in the Keycloak realm will be updated again to match the keycloak.json spec. This only applies for clients that are not default Keycloak clients.
• Clients that are modified in the Keycloak custom resource spec (e.g. via oc or the Openshift console) are updated in the Keycloak realm to match
• Clients in the Keycloak realm that are not declared in the Keycloak custom resource will be deleted (as long as they are not default clients)
• Clients that are not present in the Keycloak realm but declared in the Keycloak custom resource will be created

Verification Verify that the above scenarios behave as expected

To do

• Clean up client api calls in keycloak.go as a lot of duplicate code can be extracted. Will probably do in a separate PR.

[mikenairn]

@dimitraz fyi, these changes seem to make things work https://github.com/mikenairn/keycloak-operator/commit/e255ad9cea6a0a95367bf172a0fef3c01d002a5d

[dimitraz]

@mikenairn thanks Mike! Client reconciliation is working as expected now, updated desc with more info cc @vchepeli