Review design of list endpoints GET /edge-cloud-zones and GET /clusters and fix issues

[eric-murray]

Problem description
There are a number of issues with the design of the GET /edge-cloud-zones and GET /clusters endpoints:

• Common Issues

  • Neither endpoint supports pagination
  • Filtering by region requires use of edge cloud provider specific region names, meaning the results will be specific to a given edge cloud provider
  • Filtering by edge cloud provider is not supported
  • Documented error responses need reviewed

• GET /edge-cloud-zones issues

  • Defining a default value of unknown for status filtering prevents returning a list of edge cloud zones independent of status, thus requiring 3 separate queries to retrieve the full list

• GET /clusters

  • The response parameters provider is defined as the Application Provider (i.e. API consumer), but Kubernetes clusters are not Application Provider specific. This is surely meant to be the edge cloud provider, which is otherwise not a response parameter.
  • There is no good reason that this is a separate endpoint. The GET /clusters response data could be included as an optional response property of the GET /edge-cloud-zones endpoint, being included when relevant for the specific edgeCloudZoneId.

Expected behavior

• Fix:

  • GET /clusters response parameter provider should be edgeCloudProvider, not Application Provider
  • Remove invalid error responses as requested in Review documented error response codes #72

• Consider:

  • combining GET /clusters with GET /edge-cloud-zones into a single listing endpoint
  • including pagination support to avoid the endpoint returning large amounts of data
  • adopting geographical region identifiers for region filtering that are independent of the edge cloud provider terminology - for example, ISO 3166-1 alpha-2 country codes ("GB", "DE", "US", etc.)
  • allowing filtering by edge cloud provider
  • removing the default value of unknown for status filtering

Alternative solution
None proposed

Additional context
None