Cleanup to ScratchContainers.

Preparation for dir testing.
Added basic E2E dir copy and create tests.

Tests dir actions in a scratchdir container. Includes files, nested
dirs, empty dirs, backup triggering, mode alteration, and dir creation.
Removed uninvoked elements of DirActions.

The existing handling for dir actions that trigger a full dir backup
was entirely unused, as there are no currently supported actions
that trigger full dir backups.
Merge branch 'testing/e2e-directories' into dev