Add support for HS256 ODIC

[MilnerMart]

Summary

This pull request adds the ability to accept other token signing algorithms, especially HS256, but with the possibility of extending to other algorithms as needed.

Checklist

• I have read the BookStack community rules.
• This PR does not feature significant use of LLM/AI generation as per the community rules above.

[ssddanbrown]

Thanks for offering this @MilnerMart, but there's already an existing request to support addition signing options in #5912. This is blocked though as I feel we need to define where our bounds of support lie as my comment in #5390 (comment).
Feel free to provide input on #5390 in regard to the draft criteria, or even open a feature request issue to specifically request HS256 support.