[Cherry-pick] Move AttributionNode out of atoms.proto

Bug: 253022649
Bug: 386700524
Test: stats-log-api-gen-test
Test: m statslog-textclassifier-java-gen
(cherry picked from https://android-review.googlesource.com/q/commit:a24ed2ef058d07416bd1c44bf39d195f61992c24)
(cherry picked from https://android-review.googlesource.com/q/commit:fdadd87bbc9fc189c393f7e0998eaf10f9a7cb11)
Merged-In: Ibe7a3da69110875e3a56f0d9799150f80763c29a
Change-Id: Ibe7a3da69110875e3a56f0d9799150f80763c29a
6 files changed
tree: 374b7c0f56fdd7599885abd1bd032a20199abe17
  1. stats/
  2. OWNERS