Add scenario-specific, intuitive exceptions.

**Description:**
Currently, the OIDC SDK has three main exception classes. **SSOAgentException**, **SSOAgentSeverException** and **SSOAgentClientException**. It would be an improvement if we can have scenario specific/ intuitive exceptions for better comprehension.
eg: IDTokenValidationException, SSOAgentConfigurationException etc.

Start by reviewing the OIDC SDK's existing SSOAgentException, SSOAgentSeverException, and SSOAgentClientException classes and tracing where they are used. Define the scenario-specific exception categories, including IDTokenValidationException and SSOAgentConfigurationException, and confirm the expected scope with maintainers. Done means the exception model is agreed and consistently applied across the relevant SDK behavior.

Written by the indexing model from the issue text.