Improve snapshot test coverage

[thejchap]

Tryke uses insta for snapshot tests

Right now snapshot tests are pretty narrow - they fire on_test_complete to one of the reporters and assert the output

These should be more end-to-end tests that:

1. write project contents to a temp dir (kind of like this)
2. test the CLI end-to-end

Examples here

Additionally, I think having the explicit snapshot definitions in code in string literals (like the examples above) would be nice.

Once the tests are more end-to-end, add more test coverage. Some ideas:

• All the reporters
• Combinations of different CLI flags
• output of graph and graph --fixtures