Export gki/testdata/testkey_rsa4096.pem to Bazel rules. am: 2208a03d87

Original change: https://android-review.googlesource.com/c/platform/system/tools/mkbootimg/+/2128235

Change-Id: Ie50214faf8f0f73b1ad3cbd3eeeef32717fe5c64
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>