Consolidate main dictionary files.

This change is a preparation for upcoming optimizations on dictionary file loading.
* We can consolidate dictionary files because we are no longer relying on Asset Manager.
* Stopping compressing dictionary files as planning to use mmap() on the region in the apk file.
* Probably we won't rely on Asset Manager.  Instead we'll probably use offset and size obtained from AssetFileDescriptor.

Change-Id: Id57dce512fd3d2397a58628f8264bd824194da76