feat(authentication-service): flexible state parameter handling in KeycloakLoginController (#2353)

* feat(authentication-service): add unit tests for KeycloakLoginController

- Introduced comprehensive unit tests for the KeycloakLoginController, covering various scenarios for state handling and redirection logic.
- Implemented tests for query generation based on request body and query parameters, ensuring correct state management.
- Validated the keycloakCallback method to ensure proper redirection with state parameters, including error handling for missing client_id and user scenarios.

* refactor(authentication-service): improve KeycloakLoginController unit tests and code structure

- Enhanced unit tests for KeycloakLoginController, focusing on state handling and redirection logic.
- Refactored code for better readability, including consistent formatting and type definitions.
- Updated request handling to ensure proper type safety and clarity in state parameter management.

Author: subhamjagurisf