Add IKeystoreService interface to keystore_service

IKeystoreService is a VINTF stability interface, and keystore2 is now
using this interface correctly from Rust.

Test: m && adb shell start keystore2
Bug: 179907868
Change-Id: I3b583df2fac7e6bca7c1875efb7650f9ea0a548c
1 file changed