DexFile: Add an API to query oat file status.

Adds DexFile.getDexFileStatus(path), which returns an opaque,
human-readable string representation of the oat file status. This
representation isn't guaranteed to be stable and can change from
release to release.

bug: 27494108

Change-Id: I5fc42225ae65eb19dcd0c619a40cf674b34fc49c
3 files changed