Support Idempotency-Key in Iceberg REST Catalog API

[dimas-b]

Is your feature request related to a problem? Please describe.

IETF draft: https://datatracker.ietf.org/doc/html/draft-ietf-httpapi-idempotency-key-header-06

Iceberg proposal (author: @huaxingao):

• doc: https://docs.google.com/document/d/1WyiIk08JRe8AjWh63txIP4i2xcIUHYQWFrF_1CCS3uw/edit?tab=t.0#heading=h.jfecktgonj1i
• email: https://lists.apache.org/thread/y91scqfd1g3yd0owbgzrr1d2hm3w78gy

Describe the solution you'd like

Polaris proposal (author: @huaxingao):

• doc: https://docs.google.com/document/d/1L5A8Cspugsk1dW4Ij4dy5wB5FKa8KnaXT0LHBJdgq9w/edit?tab=t.0
• email: https://lists.apache.org/thread/3n26zfs31oqs8f85st4j7dq7c5sy47h8

Describe alternatives you've considered

See email discussions.

Additional context

No response