enhancement(http_request): add redaction for sensitive headers

[benjamin-awd]

Summary

This PR adds redaction for sensitive headers within the http_request function.

Currently, sensitive information can be leaked at runtime when the function fails:

function call error for "http_request" at (4:263): HTTP request failed: Request failed after 3 
  retries (url: http://127.0.0.1:1/test, method: GET, headers: { "Authorization": "Bearer 
  secret_12345", "Content-Type": "application/json", "X-Api-Key": "key-67890" })

With the changes within this PR:

  function call error for "http_request" at (4:263): HTTP request failed: Request failed after 3 
  retries (url: http://127.0.0.1:1/test, method: GET, headers: { "Authorization": "***", 
  "Content-Type": "application/json", "X-Api-Key": "***" })

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

Is this a breaking change?

• Yes
• No

How did you test this PR?

Unit tests

Run VRL binary locally:
./target/debug/vrl

$ . = http_request!("http://127.0.0.1:1/test",
    method: "GET",
    headers: {
        "Authorization": "Bearer secret_12345",
        "X-Api-Key": "key-67890",
        "Content-Type": "application/json"
    }
)
function call error for "http_request" at (4:211): HTTP request failed: 
Request failed after 3 retries (url: http://127.0.0.1:1/test, method: GET, headers: 
{ "Authorization": "***", "Content-Type": "application/json", "X-Api-Key": "***" })

Does this PR include user facing changes?

• Yes. Please add a changelog fragment based on
  our guidelines.
• No. A maintainer will apply the "no-changelog" label to this PR.

Checklist

• Our CONTRIBUTING.md is a good starting place.
• If this PR introduces changes to LICENSE-3rdparty.csv, please
  run dd-rust-license-tool write and commit the changes. More details here.
• For new VRL functions, please also create a sibling PR in Vector to document the new function.

References