Allow mime-type check to be disabled on FileManager.Import

Private method checkMimeType in FileManagerService retrieves the mime-type based on the file's name, and if that fails, it relies on the blob's mime-type, but only if it's normalized. Otherwise, it tries to read the blob, and fails if the blob as no stream available. This happens for a native Google Drive document. I propose a flag to to disable the checkMimeType when importing a document. Default behavior will not be changed.

This will only be used by Web UI, as JSF UI does not rely on this operation when creating documents.