chore: treat all warnings as errors except one rule: dead-code

[advancedxy]

This commit try to fix various code/lint issues: unused import, non snake_case variables, unmatched pattern arms etc. After the fix, we can enable treating all warnings as errors.

The purpose of this commit is to reduce the warning logs when building, which is annoying to find the real errors/problems.

[zuston]

Great work. Will you fix all the enum var with camel case type?

[advancedxy]

Great work. Will you fix all the enum var with camel case type?

I annotated some of the enum with UPPER_CASES by purpose(#[allow(non_camel_case_types)]), thought it will match the Java's implementation and would be more familiar.

So in my opinion, I am in favor of that style for such enums. However I have no objections if you would like change them with camel cases.