Remove mkdirp

If our build scripts target Node 10+, we can use the builtin mkdir
function in recursive mode instead.

Author: jakebailey

package-lock.json

@@ -45,7 +45,6 @@
         "@types/glob": "latest",
         "@types/microsoft__typescript-etw": "latest",
         "@types/minimist": "latest",
-        "@types/mkdirp": "latest",
         "@types/mocha": "latest",
         "@types/ms": "latest",
         "@types/node": "latest",
@@ -72,7 +71,6 @@
         "hereby": "^1.6.0",
         "jsonc-parser": "^3.2.0",
         "minimist": "latest",
-        "mkdirp": "latest",
         "mocha": "latest",
         "mocha-fivemat-progress-reporter": "latest",
         "ms": "^2.1.3",

package.json

@@ -2,7 +2,6 @@ import del from "del";
 import fs from "fs";
 import os from "os";
 import path from "path";
-import mkdirP from "mkdirp";
 import cmdLineOptions from "./options.mjs";
 import { exec } from "./utils.mjs";
 import { findUpFile, findUpRoot } from "./findUpDir.mjs";
@@ -151,8 +150,8 @@ export async function runConsoleTests(runJs, defaultReporter, runInParallel) {
 
 export async function cleanTestDirs() {
     await del([localBaseline, localRwcBaseline]);
-    mkdirP.sync(localRwcBaseline);
-    mkdirP.sync(localBaseline);
+    await fs.promises.mkdir(localRwcBaseline, { recursive: true });
+    await fs.promises.mkdir(localBaseline, { recursive: true });
 }
 
 /**