Convert Android.mk to Android.bp

Convert two mk files to bp files simultaneously, since that
1) the first mk file (list below) calls the second
one and the the second one calls one of the modules in the first one;
2) both mk files call the certificate files which cannot be used
directly by Soong build rules.

1. KeyRotationTest/Android.mk to Android.bp;
2. KeyRotationTest/ServiceTest/Android.mk to Android.bp;
3. add a bp file to include all the certificate files to be used in
Soong build.

Bug: 186778349
Test: compared the apk files built by Make and Soong
Test: TreeHugger
Change-Id: I6807baa004e5e703f8a5a9562553256f085d35a4
Merged-In: I6807baa004e5e703f8a5a9562553256f085d35a4