Follow clippy warnings

[ytoml]

For now, we have a lot of clippy warnings left untouched. In this PR, I fixed them all but below (just suppressing with attributes).

To avoid API Breaking changes: module/crate level

• clippy::derive_hash_xor_eq for erg_type
• clippy::large_enum_variant for erg_compiler, erg_parser, erg_compiler
• clippy::result_unit_err for erg_compiler/context

local

• clippy::result_unit_err in erg_common/tsort.rs
• clippy::should_implement_trait in erg_parser/ast.rs, lex.rs
• clippy::wrong_self_convention in erg_compiler/context/compare.rs
• clippy::too_many_arguments in erg_compiler/context/mod.rs

To preserve readability:

• clippy::too_many_arguments in erg_compiler/context/mod.rs
• clippy::needless_range_loop in erg_common/levenshtein.rs
• clippy::useless_conversion in erg_compiler/context/compare.rs (to keep explicit into_iter as coding rule requires)

@mtshiba

[ytoml]

And now we can set CI for clippy after this PR.

[mtshiba]

I added clippy checks to pre-commit and GitHub Actions. Thank you!