EQL v3 jsonb_path_query does not aggregate array entries

[tobyhede]

eql_v3.jsonb_path_query returns one row per matching array entry. Downstream
array operations therefore receive a single entry instead of one gathered array
document; for example, a two-element array can report a length of one.

EQL v2 gathered entries sharing the array selector before returning them. The v3
surface needs equivalent container-based aggregation while preserving domain
typing and scalar path-query behaviour.

Acceptance criteria

• A path query selecting a two-element encrypted array returns one array result.
• jsonb_array_length(jsonb_path_query(...)) returns two for that result.
• jsonb_array_elements expands the gathered result exactly once.
• The JSON path functions remain inlinable and have regression coverage for
  planner shape as well as correctness.
• The fix follows the umbrella array wire contract and does not reintroduce an
  unauthenticated array marker.