feat: add single and batch storage calls (TNTP-9261)

[vakhov]

Adds crud.storage_call() and crud.storage_call_many() to invoke named stored functions on storage masters through regular net.box.call, without exposing vshard to clients.

Routing supports an explicit bucket_id or a space primary key, including custom sharding keys and functions. Single calls use callrw(). Batch calls use map_callrw() with split arguments and concurrent dispatch to affected replicasets.

• Target functions must have a persistent body and setuid = false. Execution and result serialization preserve the original caller’s privileges.
• Batch results retain input order.
• Stored functions manage their local transactions. Open transactions are rolled back; execution on that storage stops if cleanup cannot complete.
• Individual function errors do not stop other items. Ref/Map infrastructure errors return a top-level error without partial results; committed changes remain committed.
• CRUD does not automatically retry target functions. Ambiguous completion is marked with may_have_side_effects = true.
• Additional bucket references protect running handlers after the router stops waiting.

TNTP-9261.