fix: Error messages when Terraform validation fails due to bad credentials

[aron]

• Ready for review
• Follows CONTRIBUTING rules
• Reviewed by Snyk internal team

What does this PR do?

Fixes CC-751

Handles 401 authentication errors when making a validation request to Terraform, previously we would always return a result regardless of the HTTP response, this resulted in misleading error messages.

This PR also fixes the type definition of the request() function so the caller no longer has to unwrap the returned response from the promise. The return type for the non-callback approach is now Promise<{res: NeedleRes, body: any}> instead of Promise<void | {res: NeedleRes, body: any}>

Where should the reviewer start?

All the code is in src/lib/iac/iac-parser.ts, we have no unit tests for this code path :/ and it will all soon be replaced by the --experimental branch.

How should this be manually tested?

1. Invalidate the API token e.g. `snyk config set api=foo`
2. Test a Terraform file e.g `node ./dist/cli iac test ./test/fixtures/iac/terraform/sg_open_ssh.tf`

What are the relevant tickets?

https://snyksec.atlassian.net/browse/CC-751

Screenshots

Before

After

[github-actions]

Expected release notes (by @aron)

fixes:
Show auth error message when Terraform fails (ecb74d6)

others (will not be included in Semantic-Release notes):
Fix request type definition (b7f89aa)

• I hereby acknowledge these release notes are 🥙 AWESOME 🥙

[github-actions]

	Warnings
⚠️	You've modified files in src/ directory, but haven't updated anything in test folder. Is there something that could be tested?

Generated by 🚫 dangerJS against ecb74d6

[ipapast]

Ran it locally with invalid token. works with a nice message :)