hx/unpack-streaming (was: What's cooking in git.git (Jun 2022, #07; Wed, 22))

> * hx/unpack-streaming (2022-06-13) 6 commits
>  - unpack-objects: use stream_loose_object() to unpack large objects
>  - core doc: modernize core.bigFileThreshold documentation
>  - object-file.c: add "stream_loose_object()" to handle large object
>  - object-file.c: factor out deflate part of write_loose_object()
>  - object-file.c: refactor write_loose_object() to several steps
>  - unpack-objects: low memory footprint for get_data() in dry_run mode
>
>  Allow large objects read from a packstream to be streamed into a
>  loose object file straight, without having to keep it in-core as a
>  whole.
>
>  Will merge to 'next'?
>  source: <cover.1654914555.git.chiyutianyi@gmail.com>