DngCreator: Handle off-by-1 issue for DNG rects

In DNG sdk, rectangle's bottom and right are exclusive.
Update DngUtils to be consistent with that.

Also fixed normalized optical center calculation given pixel [0, 0]
is a square centered at (0.5, 0.5).

Test: DngCreatorTest, and visually inspect DNG images taken
Bug: 119566614
Change-Id: I73ab9327f75c24282ae14ef798fef797bb700bae