feat(cli): allow specifying name of provisioner daemon (#11077)

- Adds a --name argument to provisionerd start
- Plumbs through name to integrated and external provisioners
- Defaults to hostname if not specified for external, hostname-N for integrated
- Adds cliutil.Hostname

enterprise/cli/testdata/coder_provisionerd_start_--help.golden

@@ -9,6 +9,10 @@ OPTIONS:
   -c, --cache-dir string, $CODER_CACHE_DIRECTORY (default: [cache dir])
           Directory to store cached data.
 
+      --name string, $CODER_PROVISIONER_DAEMON_NAME
+          Name of this provisioner daemon. Defaults to the current hostname
+          without FQDN.
+
       --poll-interval duration, $CODER_PROVISIONERD_POLL_INTERVAL (default: 1s)
           Deprecated and ignored.