Static IPs for Gateways

[shaneutt]

In order for Gateway API to release v1.0.0 we need conformance tests for all things core and extended. One extended feature available for GA is the ability to statically assign addresses to a created Gateway resource rather than allowing those IPs to be dynamically provisioned:

kubernetes-sigs/gateway-api#2035

The purpose of this task is to implement this functionality in Blixt, which supports both kubernetes-sigs/gateway-api#2035 and #81, as well as kubernetes-sigs/gateway-api#1794 and kubernetes-sigs/gateway-api#1792.

After this is implemented, we need to plug the upstream conformance test suite into Blixt and start running Gateway API conformance tests as a part of our CI, at least to the level of Gateway conformance for this iteration.

Acceptance Criteria

• Static IP addresses from a known pool for my Service provider can be used for Gateways
• Support for static IPs on Gateways depends on the Service provider in Blixt, if the underlying provider does NOT support doing this make sure the Gateway status reflects this and if the IP is removed becomes eventually consistent