Add full integration test for tuono new CLI command

[Valerioageno]

This task is the next piece of #398 and covers the creation of the testing suite for the tuono new command.

It requires the followings:

• New file crates/tuono/tests/cli_new.rs
• Mock a temporary empty folder (you can use the utility in tests/utils.rs)
• Mock the GitHub APIs (this two crates look pretty cool -> wiremock | httpmock)
• Run tuono new and assert the output

[Robert-maker1994]

I can look at this, I was reading about wiremock in a [https://rust-exercises.com/advanced-testing/07_http_mocking/01_basics](Rust book). Looks to provide what we need, but illk at httpmock as well.

I'm unsure how to assign myself in this issue.

[Valerioageno]

Thanks for it! I assigned yourself to it (needs permissions)