Homestyx hydra

R1:55a698a28a75

Use HTTPEngineExtension proxy for `git` HTTP operations

Summary: Ref T10227. When we perform `git` http operations (fetch, mirror) check if we should use a proxy; if we should, set `http_proxy` or `https_proxy` in the environment to make `git` have `curl` use it.

Test Plan:
- Configured a proxy extension to run stuff through a local instance of Charles.
- Ran `repository pull` and `repository mirror`.
- Saw `git` HTTP requests route through the proxy.

Reviewers: chad

Reviewed By: chad

Maniphest…
Repository: R1 hydra
Commit Date: Jun 9 2016