Fix all clippy lints in arrow crate

[alamb]

Describe the bug
Due to "historical reasons" there are several clippy lints that are disabled in the arrow crate
https://github.com/apache/arrow-rs/blob/master/arrow/src/lib.rs#L130-L141

#![allow(dead_code)]
#![allow(non_camel_case_types)]
#![deny(clippy::redundant_clone)]
#![allow(
    // introduced to ignore lint errors when upgrading from 2020-04-22 to 2020-11-14
    clippy::float_equality_without_abs,
    clippy::type_complexity,
    // upper_case_acronyms lint was introduced in Rust 1.51.
    // It is triggered in the ffi module, and ipc::gen, which we have no control over
    clippy::upper_case_acronyms,
    clippy::vec_init_then_push
)]

It would be great to clean up the code to pass these lints for tidiness

To Reproduce
Remove one of the #[allow] lines above, run clippy

Expected behavior
Clippy runs cleanly without blank #allow across the whole crate

Additional context
Add any other context about the problem here.

[gsserge]

I'd like to work on this one. One PR per lint rule should make it easier to review and integrate.

[alamb]

Thanks @gsserge that would be great!