Add v1->v3 cluster migration

[alexander-demicev]

What this PR does / why we need it: This PR allows migrating from V1->V3 cluster without reimporting the clusters. Rancher already creates a V3 cluster for every V1 cluster. V3 cluster controller will check that V1 cluster includes a migrated annotation or exists at all for a given v3 cluster if the annotation is present, the reconciliation will continue as expected. Users are required to set proper labels on the existing V3 cluster before migrating, this will be described in the ADR and rancher turtles docs.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged): Fixes #

Special notes for your reviewer:

Checklist:

• [ ] squashed commits into logical changes
• [ ] includes documentation
• [ ] adds unit tests
• [ ] adds or updates e2e tests

[salasberryfin]

Thanks @alexander-demicev, LGTM. I pushed some minor changes to fix CI checks and I'm fixing E2E tests locally and will be pushing an update too.

[furkatgofurov7]

@alexander-demicev is this a duplicate of https://github.com/rancher/turtles/pull/576 ?

[salasberryfin]

Hey @furkatgofurov7, #576 implements the approach presented by @Danil-Grigorev, which will be considered the primary migration method. The changes proposed in this PR will allow us to also support manual migration of clusters and it will also help with avoiding breaking clusters when users do not follow the proper migration procedure, i.e. prevent from creating duplicate resources to represent the same CAPI cluster.

[salasberryfin]

Thanks for the review @Danil-Grigorev. Only E2E is pending for this to be ready to be merged.