fix(api-gateway): support proxy when fetching jwk for token validation

[johnsca]

Check List

• Tests has been run in packages where changes made if available
• Linter has been run for changed code
• Tests for the changes have been added if not covered yet
• Docs have been added / updated if required

Description of Changes Made (if issue reference is not provided)

When fetching the JWK data needed to validate the auth token, the environment proxy settings are not honored.

[igorlukanin]

@johnsca Thanks for this contribution!

the environment proxy settings are not honored

Just to double check, which proxy settings exactly are not honored? Also, which platform are we talking about here?

[johnsca]

@igorlukanin

Just to double check, which proxy settings exactly are not honored? Also, which platform are we talking about here?

No proxy settings were being honored when using JWT authentication (specifically, when retrieving the JWK keys to validate the token). This was encountered when deploying Cube in an environment with restricted outbound traffic which requires request to the public internet to go out via a proxy for security reasons.

This PR uses ProxyAgent because it supports the HTTPS_PROXY and NO_PROXY env vars, which the lower-level HttpsProxyAgent used by getHttpAgentForProxySettings() doesn't appear to. It might be worth moving that code to ProxyAgent as well, as recommended by the proxy-agents README, but I wanted to keep this PR minimal.