Keycloak-angular: Initialize Keycloak before bootstrap the application

[pahlers]

Bug Report or Feature Request (mark with an x)

- [ ] bug report -> please search for issues before submitting
- [x] feature request

The KeycloakService can be initialized before the application loading. When the Keycloak initialization is successful the application is bootstrapped.

This had two major benefits.

1. This is faster because the application isn't fully bootstrapped and
2. it prevents a moment when you see the application without having the authorization.

[mauriciovigolo]

Hello @pahlers, thanks for contributing! Really enjoyed this way of loading and the benefits.
Will be merged for the @next release :)

[pahlers]

Splendid! Big thanks!

[mauriciovigolo]

Included on [email protected]. Thank you @pahlers!