Add an explicit classpath file for ravenwood-runtime

Instead of depending on alphabetical order of jars in a folder, we now
define the order of the jars in a text file.

Bug: 292141694
Flag: EXEMPT host side change only
Test: f/b/r/scripts/run-ravenwood-tests.sh
Change-Id: I1af33b3ee0b9ad3b757de5f3985ee1e6bbd96dc1