⚠️ Implement v1beta1 ↔ v1beta2 conversion webhooks

[bnallapeta]

What this PR does / why we need it:

• Move Hub markers from v1beta1 to v1beta2, making v1beta2 the conversion hub
• Implement ConvertTo/ConvertFrom for all resource types (OpenStackCluster, OpenStackMachine, and their Templates/Lists)
• Add condition format conversion between CAPI v1beta1 conditions and standard metav1.Condition
• Handle FailureDomains map↔slice conversion and deprecated field derivation

Test plan

• make test passes (348 tests)
• make lint passes
• Unit tests for round-trip conversion of all types
• Condition conversion tests verify format mapping

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 #2940 part of #2895

Special notes for your reviewer:

To be merged after #2947

/hold

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