PBSClient: file_restore_list: add extraParams and use timeout

PBSClient: file_restore_list: add extraParams and use timeout

under some conditions, like when calling it in the api where we have
a 30s pveproxy limit, we want to make use of the '--timeout' parameter
of the file-restore binary, but we may want to call it in the future
where we don't want add timeout.

To achieve that, add an extendable 'extra_params' hash parameter to
'file_restore_list' and use the timeout from there.

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>