[layertracegenerator] fix display proto parsing

- fixes a couple of bugs in how we parsed display data
and added tests to cover the logic
- additionally create fake input tokens when
generating layer state so we don't assume that the token
is null and ignore input data

Fixes: 275418553
Test: presubmit
Change-Id: I60dd2862e0c6ce0e214ad2123a8523b4f74c38e9