Move classpaths.proto related info into a separate provider.

The new info struct can be easily shared with systemserverclasspath
fragments.

Bug: 180105615
Test: m nothing
Merged-In: I9986e64fdf19f4168da63c156de3dc9bcafac8d8
Change-Id: I9986e64fdf19f4168da63c156de3dc9bcafac8d8
(cherry picked from commit 14e49130)