Export gki/testdata/testkey_rsa4096.pem to Bazel rules. am: 2208a03d87 am: 40ccb64f11 am: 0101cfe925

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

Change-Id: I1cd28a804e1bc7f7175c48d9eacaed4dfcf976b0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>