[POC] v1beta1 -> v2alpha1 migration

[strekm]

Description

APIRule v1beta1 to v2alpha migration assumes that user would need to enable migration configuration to minimise downtown transition as described here: https://github.com/kyma-project/api-gateway/issues/1092. Goal of this task is to research if it is possible to avoid additional manual user configuration in favour of automated migration.

TODO:

• [x] check if switching APIRule VirtualService from ORY Oathkeeper to workload will cause any downtime
• [x] check if it's possible to exclude using migration flag

AC:

• [x] documentation provided

Reasons

Migration automation

DoD: - [ ] Provide unit and integration tests.

• [x] Provide documentation.
• [x] Verify if the solution works for both open-source Kyma and SAP BTP, Kyma runtime. - [ ] If you changed the resource limits, explain why it was needed. - [ ] Verify that your contributions don't decrease code coverage. If they do, explain why this is the case. - [ ] Add release notes.

Attachments part of: #939

[triffer]

PoC outcome:

• It was verified that switching the virtual service from Oathkeeper to the service did not cause any downtime.
• For migration, an approach using a migration marker annotation is documented and the migration process has been verified on k3d and Gardener clusters.

A more detailed description can be found in the documentation of the PoC. The implementation and code can be found in the apirule-migration-poc branch.

[videlov]

Look good to me. Nothing to add at this point. We will refine / retest when we are doing the implementation.