test(visualizeSubnetwork): Add unit tests for visualizeSubnetwork

[tonywu1999]

Motivation and Context

We should add unit tests for the visualizeSubnetwork function, which takes nodes and edges and visualizes them on Cytoscape. Due to the nature of integration with Cytoscape, we will mock those functions.

Changes

• Add unit tests verifying basic functionality of visualizeSubnetwork and its parameters
• Added test data
• Added dependency on mockery for testing

Testing

• All tests pass

Checklist Before Requesting a Review

• [ ] I have read the MSstats contributing guidelines
• [ ] My changes generate no new warnings
• [ ] Any dependent changes have been merged and published in downstream modules

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 86.59%. Comparing base (4f4a970) to head (7c5b829).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## devel #9 +/- ## =========================================== + Coverage 59.79% 86.59% +26.80% =========================================== Files 3 3 Lines 97 97 =========================================== + Hits 58 84 +26 + Misses 39 13 -26 ```

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