Intention Request Notification

#### Feature Description
In the situation of multi tenancy, it would be nice if an application owner could "request" an intention be added to allow their service to speak to another, at which point some type of marking would be denoted on the requested service to see that they have a request to allow/deny a service.

#### Use Case(s)

Service Mesh Use Case: Administrating a consul cluster that allows multiple teams/applications on it, to allow those teams to more easily communicate and add/remove intentions between each other.

Start with the feature description and service-mesh use case, then clarify how an owner submits a request, how the target service sees it, and how approval or denial is recorded. Define the request lifecycle and acceptance criteria before locating the relevant Consul intention and API entry points; done should include a complete, reviewable request workflow.

Written by the indexing model from the issue text.