Status API: use consistent status schema

[shashankram]

kgateway version

Is your feature request related to a problem? Please describe.

When designing the status API, it would be desirable to ensure the status API for all kgateway objects have a mostly consistent schema.

Describe the solution you'd like

Something like the below would be good enough for a majority of use cases:

status:
  # list of conditions describing state transitions
  conditions:
  - type: SomeCondition
    status: "True"
    message: "foo bar"
    reason: FooBar
    lastTransitionTime: "2025-03-05T00:00:10Z"

 # Aggregate phase
 phase: SUCCEEDED|FAILED|PENDING|UNKNOWN

A printer column for status.phase to easily lookup the aggregate phase of the resource.

Describe alternatives you've considered

No response

Additional Context

No response