docs: add adr for v1 to v3 controller migration

[salasberryfin]

kind/documentation

What this PR does / why we need it:

This is a work-in-progress.

Which issue(s) this PR fixes: Fixes #

Special notes for your reviewer:

Checklist:

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

[salasberryfin]

Thanks @alexander-demicev @Danil-Grigorev. I added references to the original v3 controller ADR where relevant.

[salasberryfin]

Added reference to automatic migration ADR and cluster-api.cattle.io/owned label. I think it is ready for a final review.

[furkatgofurov7]

Merging this as this is just a documentation PR and there is no point of running/waiting for E2E tests