Add translation for GKE Ssl Policy

[sawsa307]

What type of PR is this?
/kind feature

What this PR does / why we need it:
Adding a new feature for GKE Ingress and Gateway conversion.

Which issue(s) this PR fixes:
Adding more feature for #87.

Does this PR introduce a user-facing change?:

Ingress2gateway now supports translating Ssl Policy on GKE Ingress to GCPGatewayPolicy on GKE Gateway.

[sawsa307]

/assign @spencerhance
/assign @LiorLieberman

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: sawsa307
Once this PR has been reviewed and has the lgtm label, please ask for approval from liorlieberman. For more information see the Kubernetes Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[LiorLieberman]

Hi, just checking in, anything I can do to help with this?

Ca this be reviewed by someone from GKE?
/cc @spencerhance @robscott

[robscott]

Thanks @sawsa307! Mostly LGTM, just one nit.

[robscott]

These kinds of tests can become really difficult to follow if you have to spell out the entirety of each manifest for each test case. I'd recommend moving towards a pattern where there's a base resource that each test case makes small modifications to. Here's an example of that pattern in Kubernetes: https://github.com/kubernetes/kubernetes/blob/80941e3e87d3909aa70e4f38f37b447f4376661f/pkg/apis/storage/validation/validation_test.go#L1741.

[sawsa307]

Sounds good! Just updated based on the example.
For now I only make sure in each test case, we modify the input ingress based on a template ingress, and I'm still keeping the expected output in details to make sure we compare with to detailed outputs.