Add krb_principal option for waiverdb-cli
By default Kerberos tries to use FQDN of the server. E.g. if client.conf
contains:
[waiverdb]
auth_method=Kerberos
api_url=https://waiverdb.example.com/api/v1.0
And FQDN of "waiverdb.example.com" is "web-waiverdb.app.os.example.com"
the Kerberos principal will be
"HTTP/web-waiverdb.app.os.example.com@EXAMPLE.COM" which may not match
the principal in server's keytab.
This can be changed by using different configuration file with
`dns_canonicalize_hostname=false` setting and setting path to the file
using `KRB5_CONFIG` environment variable.
The new option `krb_principal` allows to override the Kerberos principal
in waiverdb-cli configuration file instead. E.g:
[waiverdb]
auth_method=Kerberos
api_url=https://waiverdb.example.com/api/v1.0
krb_principal=HTTP/waiverdb.example.com@EXAMPLE.COM
Signed-off-by: Lukas Holecek <hluk@email.cz>