Clippy fixes

[asibahi]

The first commit contains a bulk of basic lints (avoiding double refs, needless returns, needless format!, and so on).

The other commits are divided by lint they apply.

[RazrFalcon]

collapsible if should probably be ignored. We try to match harfbuzz's code style when possible. So the code should look as close to harfbuzz as possible, at least in theory.

[alerque]

We can configure the lint to be ignored project wide if it is interfering with keeping the cognitive load low when comparing code bases.

[asibahi]

These are the remaining lints. I wonder where a good place to add them would be:

// Quiet Clippy lints left to match hb style
#![allow(clippy::collapsible_if)]
#![allow(clippy::collapsible_else_if)]
#![allow(clippy::comparison_chain)]
#![allow(clippy::needless_range_loop)]
#![allow(clippy::non_canonical_partial_ord_impl)]
#![allow(clippy::doc_lazy_continuation)] // <-- this one is about docs, not code style
#![allow(clippy::upper_case_acronyms)]
#![allow(clippy::too_many_arguments)]
#![allow(clippy::wildcard_in_or_patterns)]
#![allow(clippy::identity_op)]
#![allow(clippy::mut_range_bound)]
#![allow(clippy::enum_variant_names)]
#![allow(clippy::manual_range_patterns)]
#![allow(clippy::type_complexity)]
#![allow(clippy::wrong_self_convention)]
#![allow(clippy::match_like_matches_macro)]

[RazrFalcon]

Looks fine to me, but let's also disallow (a..b).contains(&c). Since it's not available in C++. Should make porting easier.

[RazrFalcon]

Looks good. Will wait for someone to merged it.