Improve ability to test service locally

[x] Read all configuration variables in the service upon startup to detect problems as early as possible: #3136
[ ] Allow deploy.py to be run in a way which skips the ApiService deployment
[ ] Provide scripts for deployment and running of local service which automatically configures the local service to point to the deployed resources
[ ] Ability to run integration tests against live resources as part of CI?
[ ] Record-replay tests?

microsoft / onefuzz