[Feature][PPL] Report progress for asynchronous Calcite queries

[penghuo]

Parent: #5765

Goal

Report bounded, monotonic progress for every asynchronous Calcite PPL query independently of whether partial rows are available.

Scope

• Add progress.fraction_done to asynchronous submit and GET responses.
• Derive best-effort source progress from existing OpenSearch interfaces without requiring exact track_total_hits=true.
• Cover single-request search, PIT-paged search, aggregation, Composite aggregation, and multi-source plans.
• Keep progress independent from partial-result publication.

Acceptance criteria

• fraction_done is finite and always within [0.0, 1.0].
• Progress never decreases and never reaches 1.0 while status is RUNNING.
• SUCCEEDED reports 1.0; failure and cancellation retain the last running value.
• Every supported query shape reports progress, including blocking coordinator plans that cannot publish rows early.
• Progress collection does not require an exact total-hit count and keeps performance comparable with the synchronous query.
• REST tests verify monotonicity, bounds, terminal behavior, and multi-source aggregation.