Organize imports with rustfmt

[ed255]

In my last PRs I felt that the imports organization were getting out of hand.
Not only with unused imports, but in particular I haven't put the effort to have clean imports and this means lots of unstructured lines importing stuff like:

pod2/src/backends/plonky2/circuits/mainpod.rs

Lines 1 to 29 in 3b2860b

	use anyhow::Result;
	use itertools::Itertools;
	use plonky2::{
	field::types::Field,
	hash::{
	hash_types::{HashOut, HashOutTarget},
	poseidon::PoseidonHash,
	},
	iop::{
	target::{BoolTarget, Target},
	witness::{PartialWitness, WitnessWrite},
	},
	plonk::circuit_builder::CircuitBuilder,
	};
	use std::collections::HashMap;
	use std::iter;
	use crate::backends::plonky2::basetypes::{Hash, Value, D, EMPTY_HASH, EMPTY_VALUE, F, VALUE_SIZE};
	use crate::backends::plonky2::circuits::common::{
	CircuitBuilderPod, OperationTarget, StatementTarget, ValueTarget,
	};
	use crate::backends::plonky2::primitives::merkletree::{MerkleProof, MerkleTree};
	use crate::backends::plonky2::primitives::merkletree::{
	MerkleProofExistenceGate, MerkleProofExistenceTarget,
	};
	use crate::middleware::{
	hash_str, AnchoredKey, NativeOperation, NativePredicate, Params, PodType, Predicate, Statement,
	StatementArg, ToFields, KEY_TYPE, SELF, STATEMENT_ARG_F_LEN,
	};

For example here I was sloppy and I didn't merge line 22 and 23.

This chore can be easily automated with a configuration of rustfmt, so I would propose to add a rustfmt.toml file in the root with these settings:

imports_granularity = "Crate"

See https://rust-lang.github.io/rustfmt/?version=v1.8.0&search=imports_gran#imports_granularity

[arnaucube]

Would you like to tackle this @ed255 ? Till this issue I was manually organizing the imports at the files I was touching, but after this issue it feels like it is not worth spending time on it if we can automate it soon ^^

[ed255]

Would you like to tackle this @ed255 ? Till this issue I was manually organizing the imports at the files I was touching, but after this issue it feels like it is not worth spending time on it if we can automate it soon ^^

I would like to propose doing this next week. The reason is that currently we have a few open PRs and different active branches but next week we will slow down and have most things merged; so delaying this to next week will reduce the time spent resolving conflicts.

[arnaucube]

Sounds good, we can use the opportunity to also fix the clippy lints all at once.