"Chunk" is not a thing in the SOCI world

[vkuzniet]

Is your feature request related to a problem? Please describe.
The Stargz and eStargz file formats have a notion of "chunks". During the conversion step, large files are split into multiple chunks, so that they can be pulled, verified and uncompressed separately. SOCI has no such notion. In the SOCI world, layers are divided into variable sized "spans" for pulling and checksumming purposes.

Describe the solution you'd like
Any code in SOCI that refers to chunks is dead code and needs to be removed.

The solution should satisfy the following criteria:

• cd SociSnapshotter; ag chunk | wc -l returns 0
• If the above criteria cannot be satisfied, a comment is added to this story explaining why.

Describe alternatives you've considered

Additional context
See the following links for reference:

• https://github.com/google/crfs
• https://github.com/containerd/stargz-snapshotter/blob/main/docs/estargz.md

[vkuzniet]

Closing, since it's already done.