chore: storage refactors part 1

[magik6k]

Related Issues

Part 1 of #8793

Proposed Changes

• Move things in storage/ into clean sub-packages
• Move non-extern things from extern/ to packages in storage/

For the next PR (didn't want to put logic changes in this PR to avoid mixing them with a big high-noise diff):

• Remove storage/adapter_*.go
• Drop dependency on specs-storage
• Add new architecture Readme to storage/

Main moves are:

• storage/wdpost_*.go -> storage/wdpost/ - making space for other storage related packages here
• extern/sector-storage -> storage/sealer - don't pretend like this will live in a separate repo; should be much easier to find
• extern/sector-storage/stores -> storage/paths - The stores package mostly deals with paths with sectors, seems like a much more logical name.
• extern/storage-sealing -> storage/pipeline - This is the sealing pipeline; didn't want to name it sealer/sealing for the obvious reason that it sounds a bit like sealer which is already in use above.

There may be some more PRs moving things around, but this should be the biggest one, addressing the most annoying/overdue things

[geoff-vball]

The linter needs to be appeased.

Github is also complaining about some unsanitized logs, but it looks like most of these are coming from sources with admin perms anyway?