Fix some clippy catches

[Farhad-Shabani]

Summary of Bug

Reviewing the codes, came across lints that trigger cargo clippy while working with different Rust toolchains.
Also, some clippy exceptions could be swept to achieve a consistent practice as mentioned here

To Do

• Use variables directly in the format! & write! strings
• Change the type trusted_validator_set field of MisbehaviourTrustedValidatorHashMismatch to avoid large_enum_variant
• Box MockHeader and SyntheticTmBlock types of mock/host.rs
• Remove unnecessary clippy::large_enum_variant, clippy::ptr_arg, and clippy::wrong_self_convention
• Drop #[allow(clippy::too_many_arguments)]
  Note: This requires a rework of the functions with an excessive number of arguments. It can be handled in a separate issue.

Version

rustc 1.66.0 (69f9c33d7 2022-12-12)
clippy 0.1.66
clippy 0.1.67

Toolchains:

• stable-aarch64-apple-darwin
• nightly-aarch64-apple-darwin

Steps to Reproduce

rustup default nightly
cargo clippy

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