Restrict allowed clippy warnings and errors

[metaclips]

Current behavior

After this PR is merged, we will be ignoring some clippy warnings in our codes, warnings include

• #![allow(unexpected_cfgs)]
• #![allow(clippy::unconditional_recursion)]

Desired behavior

We should check across all Rust codebase and fix all clippy warnings/errors that are being bypassed

[PanGan21]

Hi! I was looking at this issue.
I removed both compiler attributes to get the warnings and see what needs to be fixed, but make lint_cargo_clippy didn't result to any warning.
How could I reproduce these warnings?