This replaces the krb5 module's options with RFC 42-style krb5.settings
option, while greatly simplifying the code and fixing a few bugs,
namely:
- #243068 krb5: Configuration silently gets ignored when set by
multiple modules
- not being able to use mkIf etc. inside subattributes of
krb5.libdefaults, e.g. krb5.libdefaults.default_realm = mkIf ...
See #144575.
Closes#243068.
Co-authored-by: h7x4 <h7x4@nani.wtf>
Allow switching out kerberos server implementation.
Sharing config is probably sensible, but implementation is different enough to
be worth splitting into two files. Not sure this is the correct way to split an
implementation, but it works for now.
Uses the switch from config.krb5 to select implementation.
