Fixes for r72024:

Fixes for r72024:
* Renamed MediaHandler::verifyFileHook() to verifyUpload() since it isn't a hook and the fact that it operates on files is obvious.
* Separated some concerns by simply passing verifyUpload() function a file path instead of an UploadBase object and MIME type. This simplifies the implementation of subclasses, makes the function accessible to non-UploadBase callers, and avoids breaking the interface constantly due to UploadBase changes.
* Have verifyUpload() return a Status object instead of allowing the idiosyncratic and feature-poor error array convention from UploadBase to infect MediaHandler.

The required update to PagedTiffHandler will be in a subsequent commit.