Update kotlinc to 1.7.20 am: 4e3c9ce7ac am: 2383925909 am: 0ccc8fd91c

Original change: https://android-review.googlesource.com/c/platform/external/kotlinc/+/2055028

Change-Id: Icee45c9aa181ec6bc0b6f807b88f8483fdfabc3a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>