chromite/api: add guest VM as an image type

A guest image is a VM image designed to be run in a host Chrome OS system via
crosvm. This image type takes a Chrome OS base or test image and converts it to
a VM image using the termina_build_image.py script.

BUG=b:143709253
TEST=api/contrib/gen_call_scripts (image_create,
artifacts__bundle_image_archives)

Cq-Depend: chromium:1894127
Change-Id: Ia104c69db9f3e9779e262088016be8a5db430692
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1893446
Tested-by: Trent Begin <tbegin@chromium.org>
Reviewed-by: Alex Klein <saklein@chromium.org>
Commit-Queue: Trent Begin <tbegin@chromium.org>
diff --git a/api/controller/artifacts.py b/api/controller/artifacts.py
index 3347bab..11d88d9 100644
--- a/api/controller/artifacts.py
+++ b/api/controller/artifacts.py
@@ -411,7 +411,7 @@
   """Tar VM disk and memory files.
 
   Args:
-    input_proto (SysrootBundleRequest): The input proto.
+    input_proto (BundleVmFilesRequest): The input proto.
     output_proto (BundleResponse): The output proto.
     _config (api_config.ApiConfig): The API call config.
   """