Fixed: [sc-26355] Attempt to de-escalate SAML login and logout errors

[uberbrady]

The SAML login and logout process are both pretty solid, but they do occasionally throw errors when there's some kind of misconfiguration. This ends up resulting in error 500 pages being returned to the user rather than a 4xx. Additionally, it adds a lot of 'noise' to our internal Rollbar tooling, and those errors aren't ones that we, ourselves can fix - only the customer can.

This change wraps the login and logout methods within a try/catch, and dumps a warning in the Laravel log (rather than an 'error').

Additionally, one of the SAML methods had an incorrect signature in its docblock that was making PHPStorm slightly annoyed, so I fixed that while I was there.

I was able to test the 'happy path' here and do a SAML login and logout on my local which worked OK.

[what-the-diff]

PR Summary

• Improved Exception Handling in SamlController
  We've strengthened the method to handle unexpected situations in SamlController. Now, both processResponse and processSLO methods are equipped with exception handlers in the acs and sls functions respectively.
• Added Warning Logging
  In the event of any unexpected behavior, the system will now record these occurrences in a log with a warning level, providing us with valuable information to trace and resolve any issues.
• Updated logging severity
  We've also adjusted the severity of error logs from error to a warning level. This change will help prioritize critical issues while ensuring we capture and record less critical but still significant incidents for review.
• Improve user redirection
  The user redirection route after an operation in our acs function has been updated. We've also revised the error message, enhancing our communication with users during unforeseen circumstances.
• Refined Comment and Return Type in Saml's getSetting Method
  The getSetting method in Saml has been made clearer by adding an author's comment. It's easier now to understand the wring and intent of the coder. Furthermore, we've also refined the return type of the method from void to mixed, adding flexibility and adaptability to the method's response.

[snipe]

Looks great, thank you!