Collect unused imports in ethers-v5 (#547)

* Exclude unused imports from being added to the type file (#543)

* Collect used imports in ethers-v5 target

* Add changeset

Co-authored-by: Arseniy Ivanov <138289+freeatnet@users.noreply.github.com>

Author: hasparus

Diff for: .changeset/twelve-turtles-double.md

@@ -0,0 +1,6 @@
+---
+'@typechain/ethers-v5': patch
+'typechain': patch
+---
+
+Ethers V5 target doesn't emit unused imports anymore.

Diff for: packages/hardhat-test/typechain-types/Counter.ts

@@ -1,30 +1,22 @@
 /* Autogenerated file. Do not edit manually. */
 /* tslint:disable */
 /* eslint-disable */
-
 import {
-  ethers,
-  EventFilter,
-  Signer,
-  BigNumber,
-  BigNumberish,
-  PopulatedTransaction,
   BaseContract,
+  BigNumber,
+  BytesLike,
+  CallOverrides,
   ContractTransaction,
   Overrides,
-  CallOverrides,
+  PopulatedTransaction,
+  Signer,
+  utils,
 } from "ethers";
-import { BytesLike } from "@ethersproject/bytes";
+import { FunctionFragment, Result, EventFragment } from "@ethersproject/abi";
 import { Listener, Provider } from "@ethersproject/providers";
-import { FunctionFragment, EventFragment, Result } from "@ethersproject/abi";
-import type {
-  TypedEventFilter,
-  TypedEvent,
-  TypedListener,
-  OnEvent,
-} from "./common";
-
-export interface CounterInterface extends ethers.utils.Interface {
+import { TypedEventFilter, TypedEvent, TypedListener, OnEvent } from "./common";
+
+export interface CounterInterface extends utils.Interface {
   functions: {
     "countDown()": FunctionFragment;
     "countUp()": FunctionFragment;