system_api: Add D-Bus constants and protos for Private Computing

This CL adds the D-Bus constants and the requests/responses protos that
are communicating between Ash Chrome and the D-Bus service of the
Private Computing daemon.

BUG=chromium:1367021
TEST=USE=test emerge-hatch chromeos-base/system_api

Change-Id: I6586be6cedd168d7741af7b4a14fa6978877ab6f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/3946799
Reviewed-by: Hirthanan Subenderan <hirthanan@google.com>
Commit-Queue: Eric Wang <qianwan@google.com>
Tested-by: Eric Wang <qianwan@google.com>
Reviewed-by: Eric Caruso <ejcaruso@chromium.org>
NOKEYCHECK=True
GitOrigin-RevId: b2ba2cac32bbbeac0e2c783793ec91543956294b
diff --git a/system_api.pc b/system_api.pc
index dc3a4bc..3f03c68 100644
--- a/system_api.pc
+++ b/system_api.pc
@@ -1,4 +1,4 @@
 Name: system_api
 Description: Protobuffers and headers shared by Chromium OS and Chromium.
 Version: 0.1
-Libs: -lsystem_api-hps-protos -lsystem_api-power_manager-protos -lsystem_api-authpolicy-protos -lsystem_api-biod-protos -lsystem_api-protos -lsystem_api-kerberos-protos -lsystem_api-login_manager-protos -lsystem_api-lorgnette-protos -lsystem_api-smbprovider-protos -lsystem_api-vm_concierge-protos -lsystem_api-vm_applications-protos -lsystem_api-vm_disk_management-protos -lsystem_api-vm_launch-protos -lsystem_api-vm_sk_forwarding-protos -lsystem_api-vm_cicerone-protos -lsystem_api-seneschal-protos -lsystem_api-oobe_config-protos -lsystem_api-runtime_probe-protos -lsystem_api-dlcservice-protos -lsystem_api-update_engine-protos -lsystem_api-vm_plugin_dispatcher-protos -lsystem_api-u2f-protos -lsystem_api-chunneld-protos -lsystem_api-system_proxy-protos -lsystem_api-vm_permission_service-protos -lsystem_api-anomaly_detector-protos -lsystem_api-minios-protos -lsystem_api-dlp-protos -lsystem_api-rmad-protos -lsystem_api-fusebox-protos -lsystem_api-privacy_screen-protos -lsystem_api-cdm_oemcrypto-protos -lsystem_api-ml-protos -lsystem_api-lvmd-protos -lsystem_api-shadercached-protos -lsystem_api-spaced-protos -lsystem_api-imageloader-protos -lsystem_api -lsystem_api-arc-protos
+Libs: -lsystem_api-hps-protos -lsystem_api-power_manager-protos -lsystem_api-authpolicy-protos -lsystem_api-biod-protos -lsystem_api-protos -lsystem_api-kerberos-protos -lsystem_api-login_manager-protos -lsystem_api-lorgnette-protos -lsystem_api-smbprovider-protos -lsystem_api-vm_concierge-protos -lsystem_api-vm_applications-protos -lsystem_api-vm_disk_management-protos -lsystem_api-vm_launch-protos -lsystem_api-vm_sk_forwarding-protos -lsystem_api-vm_cicerone-protos -lsystem_api-seneschal-protos -lsystem_api-oobe_config-protos -lsystem_api-runtime_probe-protos -lsystem_api-dlcservice-protos -lsystem_api-update_engine-protos -lsystem_api-vm_plugin_dispatcher-protos -lsystem_api-u2f-protos -lsystem_api-chunneld-protos -lsystem_api-system_proxy-protos -lsystem_api-vm_permission_service-protos -lsystem_api-anomaly_detector-protos -lsystem_api-minios-protos -lsystem_api-dlp-protos -lsystem_api-rmad-protos -lsystem_api-fusebox-protos -lsystem_api-privacy_screen-protos -lsystem_api-cdm_oemcrypto-protos -lsystem_api-ml-protos -lsystem_api-lvmd-protos -lsystem_api-shadercached-protos -lsystem_api-spaced-protos -lsystem_api-imageloader-protos -lsystem_api -lsystem_api-arc-protos -lsystem_api-private_computing-protos