feat(abstract-utxo): use internal coin impls and modern fs/promises

Use internal coin implementations from abstract-utxo instead of the
sdk modules for test files. Replace fs-extra with node's fs/promises.

Issue: BTC-2652

Co-authored-by: llm-git <llm-git@ttll.de>

Author: OttoAllmendinger

modules/abstract-utxo/test/unit/recovery/mock.ts

@@ -1,10 +1,10 @@
 import { bitgo } from '@bitgo/utxo-lib';
 import { AddressInfo, TransactionIO } from '@bitgo/blockapis';
 import * as utxolib from '@bitgo/utxo-lib';
-import { Bch } from '@bitgo/sdk-coin-bch';
-import { Bsv } from '@bitgo/sdk-coin-bsv';
 
 import { AbstractUtxoCoin, RecoveryProvider } from '../../../src';
+import { Bch } from '../../../src/impl/bch';
+import { Bsv } from '../../../src/impl/bsv';
 
 type Unspent<TNumber extends number | bigint = number> = bitgo.Unspent<TNumber>;
 export class MockRecoveryProvider implements RecoveryProvider {

modules/abstract-utxo/test/unit/util/fixtures.ts

@@ -1,7 +1,6 @@
 import 'should';
 import * as mpath from 'path';
-
-import * as fs from 'fs-extra';
+import * as fs from 'fs/promises';
 
 import { AbstractUtxoCoin } from '../../../src';
 
@@ -22,7 +21,7 @@ async function getFixtureWithName<T>(name: string, defaultValue: T, rawCoinName:
     if (e.code !== 'ENOENT') {
       throw e;
     }
-    await fs.mkdirp(dirname);
+    await fs.mkdir(dirname, { recursive: true });
   }
   try {
     let textContent = await fs.readFile(path, 'utf8');