Added keytab file path configuration for Kerberos in config.xml

Why it matters

This feature allows users to configure Kerberos authentication more flexibly by explicitly specifying the service keytab file location. It improves security and integration with Kerberos environments by providing direct control over the keytab path used for authentication.

How to use it

To use this feature, add the keytab parameter inside the kerberos section of config.xml, specifying the full path to your service keytab file. For example:

<kerberos>
    <keytab>/path/to/service.keytab</keytab>
    <!-- other kerberos settings -->
</kerberos>