Add "Programmed" Gateway condition, move "Ready" to extended conformance

[mikemorris]

What would you like to be added:

• Add a new "Programmed" status condition and reason to:
  • ListenerConditionType
  • ListenerConditionReason
  • GatewayConditionType
  • GatewayConditionReason
• Update the description for the "Ready" condition to note the stricter behavior and that it is now extended conformance on:
  • ListenerConditionType
  • GatewayConditionType
  • Update GatewayConditionReason "Pending" to note it should be used with the "Ready" condition when status is "Unknown", refs Add Pending reason to GatewayClass, Gateway, Listener, and Routes #1453 (comment)
• Update all conformance tests that check the "Ready" Gateway or Listener condition to check "Programmed" instead.

Adding a "Ready" reason to HTTPRoute is not in scope for this, and is tracked separately in #1156

Why this is needed:

GEP-1364 clarified that the behavior currently expressed by the "Ready" condition should instead be conveyed through a new "Programmed" condition, and "Ready" should move to extended conformance and become stricter, indicating that the data plane is able to handle requests NOW, rather than "soon".

[mikemorris]

/area conformance

[LCaparelli]

I'd like to work on this one :-)

/assign

[LCaparelli]

As per our conversation on Slack, Gateway's Accepted condition should also have its description adjusted to not require any kind of scheduling on underlying infrastructure, preventing any overlap with the new Programmed condition.