Expose SharedLibraryInfo#getAllCodePaths as @TestApi.

The method is called by CTS helper app to list all java shared libraries
present on the device. All classes present in the reported jar/apk files
are then collected by a CTS/GTS EDI collector.

Bug: 187823488
Test: m
Change-Id: I750065112d70bc3ab45c8b6c6cc8aa4d429488a8