Ensure Consistency of Filesystem After Database Write Mirroring for Schema2 Manifests

Context

During the experimental phase of the metadata database development process, we're continue to mirror writes to the filesystem in order to provide a way to preserve the state of large scale testing environments. Allowing the database to be quickly disabled, without having to transfer the data written while the database was active.

This MR adds a tests that ensure that schema2 manifests that were written to the database and mirrored to the filesystem ace accessible via the filesystem alone.

Related to: #168 (closed)