Functionality Improvements for the SAML SDK

**Description:**

A few improvements have been identified for the SAML SDK which would add to the scope of the functionality that could be utilized by the developer.

**Tasks:**

The following are the main tasks that has been identified for the first phase of the improvements.

- [ ] Add support for an error page via the properties file.
A page to customize the redirect page upon error response.

- [ ] Add support for a target page.
A page to customize the redirect page upon successful authentication.

- [ ] Refactor the SSOAgentConfigs and SSOAgentConfig classes.

Start by locating the properties-file handling and the SSOAgentConfigs and SSOAgentConfig classes named in the issue. Read how authentication success and error responses currently choose redirect pages, then identify the existing tests or entry points covering those flows. Done means the requested error-page and target-page configuration work is covered and the two configuration classes are refactored without breaking current SDK behavior.

Written by the indexing model from the issue text.