test: e2e golden testing for csv command

[Bobgy]

Set up golden file testing for go-licenses csv command on example modules.
Update golden files by running: go test --update .

The example modules are copied from

• https://github.com/google/go-licenses/pull/82/files#diff-94148d1a2f964b0818fb803205c7eeb784f34bdb714da3d3feda7706d18cfd17
• feat(v2/csv): handle vendored modules as part of the main module #98

4 added examples:

• hello01 - hello world module with no dependencies
• cli02 - module that have dependencies similar to a CLI tool generated by cobra
• vendored03 - module that vendors its dependencies
• replace04 - module using replace directive

Generated licenses.csv golden files will be good examples to demonstrate new features implemented in the v2 proposal: #70 and ensure that there are no regressions.

[Bobgy]

@wlynch for review

[wlynch]

Mostly lgtm, just minor comments.