This commit sets up logging by hooking into module loading/bootstraping
process to call a new `init` function exported by the `Proxmox::Lib::{PVE,PMG}`
module, which initializes `env_logger` with its default settings.
This allows us to use `log::*` macros from Rust code.
Signed-off-by: Lukas Wagner <l.wagner@proxmox.com>
