main: Add "--monitor-fd" to write structured event data to

If supplied then structured JSON event data will be written to that file
descriptor.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

Cargo.toml

@@ -17,6 +17,7 @@ anyhow = "1.0"
 api_client = { path = "api_client" }
 clap = { version = "2.33.3", features = ["wrap_help"] }
 epoll = ">=4.0.1"
+event_monitor = { path = "event_monitor" }
 hypervisor = { path = "hypervisor" }
 libc = "0.2.86"
 log = { version = "0.4.14", features = ["std"] }