Gracefully handle invalid perl expression in CAS/SAML/OIDC
Currently, if a user inputs an invalid perl expression in:
- CAS/SAML/OIDC access rules
- CAS/SAML/OIDC macros
- OIDC scope rules
the Issuer module will fail to load, and the entire portal crashes.
We should handle this more gracefully, by disabling only the affected app/RP/SP, similarly to how vhosts handle failure in access rules.
Ideally, we should detect these conditions before saving the configuration, but I'm not sure it can be done.