Use dprint package for dtsBundler formatting rather than dprint CLI

.dprint.jsonc

@@ -1,4 +1,5 @@
 {
+    // If updating this, also update the config in dtsBundler.mjs.
     "indentWidth": 4,
     "lineWidth": 1000,
     "newLineKind": "auto",
@@ -56,6 +57,7 @@
         "**/_namespaces/**"
     ],
     // Note: if adding new languages, make sure settings.template.json is updated too.
+    // Also, if updating typescript, update the one in package.json.
     "plugins": [
         "https://plugins.dprint.dev/typescript-0.90.5.wasm",
         "https://plugins.dprint.dev/json-0.19.2.wasm",

package.json

@@ -39,6 +39,8 @@
         "!**/.gitattributes"
     ],
     "devDependencies": {
+        "@dprint/formatter": "^0.3.0",
+        "@dprint/typescript": "0.90.5",
         "@esfx/canceltoken": "^1.0.0",
         "@octokit/rest": "^20.1.1",
         "@types/chai": "^4.3.16",

scripts/dtsBundler.mjs

@@ -5,8 +5,9 @@
  * bundle as namespaces again, even though the project is modules.
  */
 
+import * as dprintFormatter from "@dprint/formatter";
+import * as dprintTypeScript from "@dprint/typescript";
 import assert, { fail } from "assert";
-import cp from "child_process";
 import fs from "fs";
 import minimist from "minimist";
 import path from "path";
@@ -475,23 +476,23 @@ if (publicContents.includes("@internal")) {
     console.error("Output includes untrimmed @internal nodes!");
 }
 
-const dprintPath = path.resolve(__dirname, "..", "node_modules", "dprint", "bin.js");
+const buffer = fs.readFileSync(dprintTypeScript.getPath());
+const formatter = dprintFormatter.createFromBuffer(buffer);
+formatter.setConfig({
+    indentWidth: 4,
+    lineWidth: 1000,
+    newLineKind: "auto",
+    useTabs: false,
+}, {
+    quoteStyle: "preferDouble",
+});
 
 /**
  * @param {string} contents
  * @returns {string}
  */
 function dprint(contents) {
-    const result = cp.execFileSync(
-        process.execPath,
-        [dprintPath, "fmt", "--stdin", "ts"],
-        {
-            stdio: ["pipe", "pipe", "inherit"],
-            encoding: "utf-8",
-            input: contents,
-            maxBuffer: 100 * 1024 * 1024, // 100 MB "ought to be enough for anyone"; https://github.com/nodejs/node/issues/9829
-        },
-    );
+    const result = formatter.formatText("dummy.d.ts", contents);
     return result.replace(/\r\n/g, "\n");
 }