Missing enums for `GatewayClassConditionType` and `GatewayClassConditionReason`

[aharbis]

Missing enums for GatewayClassConditionType and GatewayClassConditionReason.

Expected them to exist in the following modules, similar to GatewayConditionType and GatewayConditionReason:

• https://github.com/kube-rs/gateway-api-rs/blob/main/gateway-api/src/apis/standard/constants.rs
• https://github.com/kube-rs/gateway-api-rs/blob/main/gateway-api/src/apis/experimental/constants.rs