Allow setting RSpec expectations on a stub with options

[inkstak]

This feature allows to verify a stubbed request has been requested with various options such as body, query or headers.

stubbed_request = stub_request(:post, "example.com")

# ... make requests ...

expect(stubbed_request).to have_been_requested.twice
expect(stubbed_request).to have_been_requested.once.with(body: {"a" => [1, 2, 3]})
expect(stubbed_request).to have_been_requested.once.with(body: {"a" => [4, 5, 6]})

The differences with setting these options before making the request is that we can create a generic stubbed request and only then verify it has been made with our expectations.

The implementation is pretty simple since it uses the already existing RequestExecutionVerifier to pass the options.

We use this as a monkeypatch in our projects since years. I think it was time to make a PR.
I you think this is an interesting feature, I'll be happy to dive deeper and add tests to the PR.