Create build status endpoint

[munishchouhan]

Add a new endpoint in builds to check the status on any build using buildid
GET /v1alpha1/builds/{buildId}/status

class design

class BuildStatus {
   static enum Status { PENDING, COMPLETED }
   String id
   Status status
   Boolean succeeded
   Instant created
   Duration duration
}

cc: @pditommaso @ewels

[pditommaso]

I've removed the FAILED in the Status enum because that can be inferred by the succeeded flag

[pditommaso]

Not this feature requires #421

[munishchouhan]

completed by #421