Merge "Add sdk/tools/BUILD.bazel to mark tools folder as a Bazel subpackage." am: a078142f86 am: 55ccd4e063

Original change: https://android-review.googlesource.com/c/platform/prebuilts/sdk/+/1677631

Change-Id: Ia0c34683ba3f00d46b6531c241f7c63acc59c025