CreateAction.test.ts: jest mock for cwd + snapshot for terminal output

[nick-pape]

Follow-up from PR #149, per @iclanton's review comments.

Tasks

• Line 96: Replace jest.spyOn(process, 'cwd') with a jest mock so it gets reset automatically between tests.
• Line 44: Dump the terminal/console output from runCreate to a Jest snapshot so regressions in CLI output are caught automatically.

References

• Wire default GitHub template source in CLI #149 (comment)
• Wire default GitHub template source in CLI #149 (comment)