Add function for adding EXIF to WebP files

Code copied from aosp/1148409 and aosp/1236647 with some minor
changes.

Original commit message:
Added code and test for WebP files
1) with EXIF data
2) without EXIF data but with other extra data
Added code and test for saving EXIF to WebP files without EXIF data
1) and have lossy encoding
2) and have lossless encoding
Also refactored test method names for better readability.

Bug: 138786288
Test: atest CtsMediaTestCases:android.media.cts.ExifInterfaceTest
Change-Id: Ib6319e1b7b6711b071542d94ebfdc4a9f80e9c16