Function readWithProgress

Reads a successful response body to an ArrayBuffer, reporting progress through a provider's DownloadOptions.onProgress as the bytes arrive.

The contract every caller can rely on:

• received never decreases between two calls.
• The first call is (0, total), before any byte arrives, so a host can tell "started" from "queued".
• Intermediate calls are throttled to about 10 Hz (PROGRESS_INTERVAL_MS).
• The last call is (byteLength, byteLength) for the buffer returned.

total is the response's Content-Length when present and usable, else fallbackTotal (typically the listing's SourceFile.sizeBytes), else undefined, in which case the host shows an indeterminate state. A total the stream outgrows is dropped rather than reported below received.

Without onProgress this is exactly response.arrayBuffer().