Add extension to swagger to capture EligibleDeploymentScopes

Right now we don't have a high-confidence way of determining which resource types are valid at which deployment scopes. We should add an extension to swagger for RP teams to capture this detail in their API definitions.

Start by locating the Swagger/API definition extension mechanism and the EligibleDeploymentScopes concept referenced in the issue. Check how RP teams currently express resource metadata and determine the expected extension shape and validation. Done means API definitions can capture which resource types are valid at each deployment scope, with the behavior documented and covered by the relevant tests.

Written by the indexing model from the issue text.