fix: remove iTunesValidator

[rigor789]

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What is the current behavior?

Currently the CLI checks if iTunes is installed on the system before calling ios-device-lib. Since macos Big Sur this no longer works, because the paths the CLI checks are not present on the filesystem anymore thus it fails.

What is the new behavior?

The CLI is no longer responsible for making the checks - it's delegated to ios-device-lib.

Fixes #5342 .