Refactor DisplayTopologyGraph to be POJO

Api lint tools couldn't properly verify Java record semantics causing
some compiler errors. To support this as a TestApi, this needs to be
modified back to plain Java objects.

Native object arrays are kept-as-is to keep it readable by JNI

Bug: 412528980
Test: atest DisplayTopologyTest
Test: atest inputflinger_tests
Test: atest WmShellUnitTests
Flag: EXEMPT refactor no new behavior change
Change-Id: I5e6d5a6a67589992b0db6171c903826ae6c7b3d0