chore: sort imports

[fedgiac]

Description

Today I learned about Foundry's sort_imports fmt configuration option.

As it has almost zero dev cost to use it, I'd go for it.

Drawback: I noticed a bug while formatting our code, specifically this section:

import {IERC20} from "src/contracts/interfaces/IERC20.sol";
import {GPv2Signing} from "src/contracts/mixins/GPv2Signing.sol";
import {GPv2Order} from "src/contracts/libraries/GPv2Order.sol";
import {GPv2Trade} from "src/contracts/libraries/GPv2Trade.sol";

was changed to:

import {IERC20} from "src/contracts/interfaces/IERC20.sol";

import {GPv2Order} from "src/contracts/libraries/GPv2Order.sol";
import {GPv2Trade} from "src/contracts/libraries/GPv2Trade.sol";
import {GPv2Signing} from "src/contracts/mixins/GPv2Signing.sol";

and I had to manually remove the extra newline.
I'd still say this isn't a big issue as we'd notice on reviewing.

Since I noticed it, I also removed a duplicate import.

Test Plan

CI doesn't fail on fmt --check.

[fedgiac]

It also makes duplicated imports like this easier to spot. (linter issue for adding a related rule here.)

[mfw78]

Also can remove the duplicate import prior to merging