Remove code of the challenge-response-auth feature

[sweep-ai[bot]]

Description

This pull request removes all code related to the challenge-response-auth feature from the command.rs and state.rs files in the trussed-secrets-app repository. The challenge-response-auth feature is no longer needed and its removal improves code cleanliness and maintainability.

Summary of Changes

• Removed all instances of the #[cfg(feature = "challenge-response-auth")] attribute and the associated code blocks in command.rs.
• Checked for any dependencies on the challenge-response-auth feature within the remaining code and addressed them as necessary.
• Removed all instances of the #[cfg(feature = "challenge-response-auth")] attribute and the associated code blocks in state.rs.
• Checked for any dependencies on the challenge-response-auth feature within the remaining code and addressed them as necessary.

Fixes #1.

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To checkout this PR branch, run the following command in your terminal:

git checkout sweep/remove-challenge-response-auth

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[szszszsz]

sweep: add a short commit to trigger CI