Add OWNERS file for SdkExtensions am: 28c6569151

Original change: https://android-review.googlesource.com/c/platform/prebuilts/module_sdk/SdkExtensions/+/1688106

Change-Id: I0f101889324b09d595a4c2b1ce0ec2d640e55bb0
tree: 45e697d3f6eb387cf1cf828d853d6eac35c24be2
  1. OWNERS