[IMPROVEMENT] Convert visualizer unit tests to integration like tests

[nitbharambe]

Problem faced

Currently each private function is being tested for parsing elements. This can be strict for this application and is less maintainable.

Improvement proposal

Convert existing tests to directly call parse_element_data. Use the topologically_full_grid fixture as it can cover all logic.

Community Meeting

• I wish to discuss this improvement in the bi-monthly PGM community meeting. Please join the PGM community meeting.