Feature Request: Add Ability to Pass Custom Header for Verification

🗣 Context

Would like to ProviderVerifier.Options to support --header <custom-header> option

💬 Narrative

When I run my PactVerifiable conforming tests
I want to be able to pass in a header option
So that I can inject the header with an authorization token

📝 Notes

According to the pact_verifier_cli documentation , passing a custom header is one of the available options.

--header <custom-header>...
            Add a custom header to be included in the calls to the provider. Values must be in the
            form KEY=VALUE, where KEY and VALUE contain ASCII characters (32-127) only. Can be
            repeated.

🏗 Design

✅ Acceptance Criteria

GIVEN header = ["Authorization" : "sometokenhere"

WHEN
ProviderVerifier.Options is initialized with custom header value

options = ProviderVerifier.Options(
            provider: provider,
            pactsSource: .broker(pactBroker),
            customHeader: header,
            logLevel: .error
        )

THEN
Provider Verification is successful and custom header to pact_verifier_cli is passed in the option list.

🚫 Out of Scope

Start by tracing ProviderVerifier.Options and how its values are turned into pact_verifier_cli arguments. Check the existing PactVerifiable provider-verification flow and confirm how options are passed to the CLI. Done means a custom header can be supplied through ProviderVerifier.Options and is included in successful provider verification.