Overview

Split the extension privilege declaration types out of the aggregation-stage static-properties IDL into a shared public IDL, so that extension aggregation stages and extension commands use the same types. Add the search index management actions to the closed action enum.

Part of SPM-4830 (Support Commands in the Extensions API).

Scope of Work

• New shared public IDL (src/mongo/db/extension/public/extension_privilege.idl) containing the resource pattern, the closed action enum, the action entry, and the required-privilege struct, moved out of extension_agg_stage_static_properties.idl.
• Append createSearchIndexes, updateSearchIndex, and dropSearchIndex to the action enum (append-only), and map each to its server ActionType.

Acceptance Criteria

• Existing agg-stage privilege declarations behave exactly as before.
• The new actions map to the correct {{ActionType}}s.

Example Test Cases

• Unit tests for each action mapping.
• An agg-stage declaration without a resource pattern is still rejected.
• Existing extension agg-stage auth tests are unchanged.

Technical Notes

• resourcePattern stays required, so declarations remain parseable by older servers.
• The IDL is a BSON contract, not a vtable, so it is independent of the API versioning work (SERVER-135392).

Depends on: none