This requires the path to the Codex modules directory
to be configurable, so we can use static manifest and
component files in tests. This is achieved by changing
the constant storing the Codex modules dir from private
to protected so it can be overridden when creating a
test module.
Bug: T350054
Change-Id: Icd3c6c5d2a82f5a5fb1c38b52e54893034e7375c
