feat: face and person detection samples (#362)

Adds the following region tags:

video_detect_person_beta
video_detect_person_gcs_beta
video_detect_faces_beta
video_detect_faces_gcs_beta

Author: telpirion

packages/google-cloud-videointelligence/.gitignore

@@ -10,3 +10,4 @@ system-test/*key.json
 package-lock.json
 .vscode
 __pycache__
+*.code-workspace