Incorrect type of agentx_perms parameter

[camillo-toselli]

The agentx_perms parameter is declared as Stdlib::Filemode type and the validation rules accept only a single file mode string (es 0755 or gu+w),
but the configuration parameter agentXPerms in snmpd.conf configuration file allows a more complex syntax ( SOCKPERMS [DIRPERMS [USER|UID [GROUP|GID]]] ) to specify the owner and the group of the agentX socket.
The complex syntax was allowed in puppet-snmp module version '4.1.0' but it is no more accepted in current (6.0.0) module version.