Update D8 and R8 to 8.3.19-dev am: 9bf0129317 am: 49105c9368 am: 42f352ac5f

Original change: https://android-review.googlesource.com/c/platform/prebuilts/r8/+/2843640

Change-Id: I9816c43c47cd07d7f3446197e212147fb4ca0f04
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>