Persistence model built around implementation details

[snazy]

Describe the bug

The persistence model (as in org.apache.polaris.core.entity) is built around assumptions for a particular implementation. It does not just define different entity types (think: catalog, namespace, table, etc) but also implementation details about cache and data consistency details. These details leak though the whole code base that has to deal with any kind of entity. This makes it extremely difficult to use another persistence backend than the one this persistence model was built for, like the "simpler KV store" mentioned in PolarisMetaStoreSession.

To Reproduce

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Actual Behavior

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Expected Behavior

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Additional context

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System information

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