Implement loginflow and triggers

[DonutsNL]

• [X] Show login buttons for each of the idp's configured;
• [X] Catch the login button pressed
• [x] make sure all sessions are captured and registered by glpisaml
• [x] make sure glpi/saml sessions are discriminated clearly
• [x] make sure the samlAuthRequest is logged in the database for debugging.
• [x] make sure the samlAuthRequest is send based on the correct configItem
• [x] make sure the SamlResponse is captured and matched with the correct IdP
• [x] make sure phpSaml errors are captured and logged
• [ ] make sure calls to excluded paths are logged in the database for debugging
• [x] make sure received samlResponse is registered in the database.
• [ ] make sure sessions can be forcefully logged out.
• [ ] Capture the SamlResponse in the ACS (acs implementation will be done in a different issue)

[DonutsNL]

Initial steps

Sneek preview

[DonutsNL]

Redid the initial loginscreen. Still need to implement the enforce option.