Add streaming query API with metadata tracking support

[bplatz]

Summary

Adds streaming query API that emits individual results as they are produced, rather than collecting all results into a vector. Supports all query types (SELECT, SELECT ONE, CONSTRUCT) and formats (FQL, SPARQL).

Note this is the same functionality in #1133 which I've closed in favor of this. That PR was based on the bm25 branch and this one is based on 'main' to aid review ease.

Key Features

• Memory efficient streaming: Results emitted individually for large result sets
• Metadata tracking: Optional :meta tracking emits final metadata map after results
• CONSTRUCT streaming: Emits ungrouped graph nodes without @graph wrapper
• Full query support: ORDER BY, GROUP BY, and aggregates (collect before emitting)
• Cache validation: Early validation rejects :cache option for streaming queries

API Functions

• fluree.db.api/query-stream - Stream query against database
• fluree.db.api/query-connection-stream - Stream query via connection

Metadata Format

When :meta true is enabled, final result is:

{:_fluree-meta {:fuel 123, :time "5ms", :policy {...}, :status 200}}