Implement MongoDB autostart and GC watching

Windows's implementation of enable_grasscutter_watcher works just fine.
systemd is pretty much standart for handling services.
No "sudo" or "pkexec" is needed, systemd does that automatically, but
since the user needs to authenticate, we can’t await service_status.

src-tauri/Cargo.toml

@@ -23,6 +23,7 @@ registry = "1.2.1"
 sudo = "0.6.0"
 
 [target.'cfg(target_os = "linux")'.dependencies]
+anyhow = "1.0.58"
 term-detect = "0.1.7"
 
 [dependencies]