proxy_agent: Use proxy-from-env for robustness

Now we support pretty much every variable under the sun along with
$NO_PROXY all correctly and with minimal code on our end.

package.json

@@ -40,6 +40,7 @@
     "@types/node": "^12.12.7",
     "@types/parcel-bundler": "^1.12.1",
     "@types/pem": "^1.9.5",
+    "@types/proxy-from-env": "^1.0.1",
     "@types/safe-compare": "^1.1.0",
     "@types/semver": "^7.1.0",
     "@types/split2": "^2.1.6",
@@ -82,6 +83,7 @@
     "limiter": "^1.1.5",
     "pem": "^1.14.2",
     "proxy-agent": "^4.0.0",
+    "proxy-from-env": "^1.1.0",
     "qs": "6.7.0",
     "rotating-file-stream": "^2.1.1",
     "safe-buffer": "^5.1.1",