[analyzer] Add call hierarchy tests for null-aware elements

Part of #56989

Change-Id: Ifd09b47fbb83519277fc6968a8edf8cdcdf76d6e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/393321
Reviewed-by: Keerti Parthasarathy <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Chloe Stefantsova <[email protected]>

Author: chloestefantsova