Log in agent retries for debugging

[ranweiler]

When making agent HTTP requests with retries and backoff, log what's happening to provide insight and debuggability.

[elee]

FWIW onefuzz respects -vvv which does show the underlying HTTP requests and retries, maybe documenting this in the usage would be helpful to some users?

The output from trying to connect to the playground the other day when it was 404-ing for me:

$ onefuzz versions check -vvv
DEBUG:onefuzz:getting info
DEBUG:urllib3.connectionpool:Starting new HTTPS connection (1): login.microsoftonline.com:443
[...]
DEBUG:urllib3.connectionpool:Starting new HTTPS connection (1): onefuzz-playground.azurewebsites.net:443
DEBUG:urllib3.connectionpool:https://onefuzz-playground.azurewebsites.net:443 "GET /api/info HTTP/1.1" 404 0
INFO:nsv-backend:request bad status code: 404
DEBUG:nsv-backend:request GET https://onefuzz-playground.azurewebsites.net/api/info None
DEBUG:urllib3.connectionpool:https://onefuzz-playground.azurewebsites.net:443 "GET /api/info HTTP/1.1" 404 0
INFO:nsv-backend:request bad status code: 404
DEBUG:nsv-backend:request GET https://onefuzz-playground.azurewebsites.net/api/info None
DEBUG:urllib3.connectionpool:https://onefuzz-playground.azurewebsites.net:443 "GET /api/info HTTP/1.1" 404 0
INFO:nsv-backend:request bad status code: 404
DEBUG:nsv-backend:request GET https://onefuzz-playground.azurewebsites.net/api/info None
DEBUG:urllib3.connectionpool:https://onefuzz-playground.azurewebsites.net:443 "GET /api/info HTTP/1.1" 404 0
INFO:nsv-backend:request bad status code: 404
DEBUG:nsv-backend:request GET https://onefuzz-playground.azurewebsites.net/api/info None
DEBUG:urllib3.connectionpool:https://onefuzz-playground.azurewebsites.net:443 "GET /api/info HTTP/1.1" 404 0
INFO:nsv-backend:request bad status code: 404
DEBUG:nsv-backend:request GET https://onefuzz-playground.azurewebsites.net/api/info None
DEBUG:urllib3.connectionpool:https://onefuzz-playground.azurewebsites.net:443 "GET /api/info HTTP/1.1" 404 0
INFO:nsv-backend:request bad status code: 404
DEBUG:nsv-backend:request GET https://onefuzz-playground.azurewebsites.net/api/info None
DEBUG:urllib3.connectionpool:https://onefuzz-playground.azurewebsites.net:443 "GET /api/info HTTP/1.1" 404 0
INFO:nsv-backend:request bad status code: 404
DEBUG:nsv-backend:request GET https://onefuzz-playground.azurewebsites.net/api/info None
DEBUG:urllib3.connectionpool:https://onefuzz-playground.azurewebsites.net:443 "GET /api/info HTTP/1.1" 404 0
INFO:nsv-backend:request bad status code: 404
DEBUG:nsv-backend:request GET https://onefuzz-playground.azurewebsites.net/api/info None