Is your feature request related to a problem? Please describe.

Support abstract unix domain can avoid many problems like file already exist, permission problem, and so on.

Describe the solution you'd like

It would be nice if cloudreve can support following configuration:

[UnixSocket]
Listen = @@cloudreve.sock

@@cloudreve.sock means abstract unix domain with padding, this way the UDS can work with HAProxy.
for the abstract unix domain without padding, the syntax should be @cloudreve.sock

Describe alternatives you've considered

Keeping the status quo

Additional context

nil