Enhance Keycloak Web Admin Console Design to Support Scalability

As current Admin Console design, there will be one client to be created for each other realm other than master during the admin console loading time.

When there is lot's of realms created since last admin console loaded, then there will be lot's of clients to be created in master realm by the API of /auth/admin/master/console/whoami, which will take considerable time to load the UI.

Even after the whoami API is loaded, there will be a _/auth/admin/realms
_ request almost after every user interaction in the UI.

Let's say that when there will be 1K realms in database, these batch data fetch would be not acceptable for the Admin UI data change.

Proposed Design for Web Admin Console
1. Web Admin Console access should just based on the admin user access token, not the

2. API _/auth/admin/realms
_ should be designed by Pagination base, and this API may also be only trigered once user reach to the page: `auth/admin/master/console/#/realms`, and this web page would also need to support pagination.

3. API /auth/admin/master/console/whoami should be desgined for per request per realm

4. We may not need to create clients like 'xxx-realm' in master realm