Add support for saving attributes for DNG files

Also add support for IMAGE_TYPE_UNKNOWN files that do not have an
identifiable file extension, but follows the TIFF specification.

Also fixes issue where certain thumbnail-only tags were not being
replaced after primary/preview/thumbnail image data was swapped.

Bug: 193010129, Bug: 193010735
Test: atest ExifInterfaceTest
Change-Id: I098cf1a0730d0cb0f1d6010a21b3ec7ada8dc6b7