Offline log viewer (OLV): inspect data directory to keep description of on-disk state in sync with Redpanda

[rystsov]

Adds data_directory_inspector.py script to detect unexpected files in the RP data directory and hooks it into ducktape tests. The goal is to identify every type of the ondisk Redpanda state and fail a test if it introduces new type of the state. It will force an author to update inspector and describe the state.

Inspector is live always in-sync version of:

• https://vectorizedio.atlassian.net/wiki/spaces/CORE/pages/159514759/Storage+Internals
• https://vectorizedio.atlassian.net/wiki/spaces/CORE/pages/251035671/Cloud+Storage+Internals

Fixes #9942

Backports Required

• [x] none - not a bug fix
• [ ] none - this is a backport
• [ ] none - issue does not exist in previous branches
• [ ] none - papercut/not impactful enough to backport
• [ ] v23.1.x
• [ ] v22.3.x
• [ ] v22.2.x

Release Notes

• none

[andrewhsu]

i'm converting this PR to draft to reduce notifications and searches for open PRs since this one is getting kinda old and has conflicts. feel free to take it out of draft when it's ready for review again.