Convert all tests to real go tests

[mengelbart]

The vnet package uses a main package and function to run tests and record stats for evaluation. If we convert it to real go test cases we can use synctest to speed up all the tests (see also #86).

@hanguyen-nuro do you have any use cases for the main function test runner or can we convert everything to go unit tests?

[hanguyen-nuro]

For my phase configuration and MP4 visualization work, I need the main() approach to generate real timing data and output files. However, I'm supportive of converting the phase parsing logic and validation to go tests with synctest for faster CI. Could we keep the main() integration test runners for data collection while adding unit tests for the phase configuration components?
cc @jiajieli-dev @lkang-nuro for viz

[mengelbart]

Sure, if you have a use case for it, we keep it. With #86 it should still be possible to use the main file. I will close this issue and try to come up with some simplifications of the current code base to reduce code duplication while keeping both main and unit tests.