Add metadata injection support to Pact JS Verifier

[canny]

Metadata injection support is currently available in Java, for example 'https://github.com/pact-foundation/pact-plugins/blob/main/examples/gRPC/metadata/provider-jvm/server/src/test/java/io/pact/example/grpc/provider/PactVerificationTest.java#L60' . This function is needed in cases such as providing an authentication token to be able to verify the contract file using "verifyProvider" if the producer service is performing token authorization.

https://pact.canny.io/admin/board/feature-requests/p/add-metadata-injection-support-to-pact-js-verifier

[canny]

This issue has been linked to a Canny post: Add metadata injection support to Pact JS Verifier 🎉

[mefellows]

This may need to move into the Pact JS project.