Release object_store 0.12.0 (API breaking) Around Feb 30 2025

[alamb]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
Per @tustvold on

• Discuss: Release object store 0.12.0 (breaking) or 0.11.2 (non breaking API) around Dec 15, 2024 #6596

and then do a breaking release late February in advance of the scheduled March breaking arrow release

Previous release:

• Release object store 0.11.2 (non API breaking) Around Dec 15 2024 #6902

Describe the solution you'd like
Let's plan for a major release

• Update version + make release notes
• Prepare release candidate + begin vote thread
• Release to crates.io

Describe alternatives you've considered

Additional context
See discussion on #6596