[MLMD] Add snapshot testing for LineageView

[kwasi]

/area metadata
/priority p0

Background

59cbf3d introduced a regression where resource descriptions were missing. Even though the PR would have required updating snapshots, the missing data would have been very noticeable in the empty descriptions.

We should add tests that handles older data where fields are in ArtifactProperties as well as newer data where fields are in ArtifactCustomProperties.

See https://github.com/kubeflow/metadata/blob/master/frontend/src/pages/ArtifactDetails.test.tsx and its import of testModel for how to construct an instance of the GetArtifactById response with the correct test data.