refactor(tvix/castore/blobsvc/chunked_reader): refactor, document r/7631

The public-consumable thing here is ChunkedReader, not ChunkedBlob.

ChunkedBlob is a helper that can be used to get a new AsyncRead, but
not AsyncSeek. It is used internally by ChunkedReader whenever the
client seeks.

Make this more obvious, by extending the documentation, and putting
ChunkedReader at the top of this file.

Also make ChunkedBlob and its methods private, and give ChunkedReader a
more useful constructor (from_chunks, instead of from_chunked_blob).

Change-Id: I2399867591df923faa73927b924e7c116ad98dc0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11079
Tested-by: BuildkiteCI
Reviewed-by: Brian Olsen <me@griff.name>
Reviewed-by: Connor Brewster <cbrewster@hey.com>

0 files changed, 0 insertions, 0 deletions