Use JSON + a typed wrapper instead of TS codegen (#1025)

Signed-off-by: William Woodruff <william@yossarian.net>

__tests__/download/checksum/update-known-checksums.test.ts

@@ -0,0 +1,27 @@
+import { promises as fs } from "node:fs";
+import os from "node:os";
+import path from "node:path";
+import { expect, test } from "@jest/globals";
+import { updateChecksums } from "../../../src/download/checksum/update-known-checksums";
+
+test("serializes checksum entries as JSON data", async () => {
+  const tempDirectory = await fs.mkdtemp(
+    path.join(os.tmpdir(), "setup-uv-checksums-test-"),
+  );
+  const outputPath = path.join(tempDirectory, "known-checksums.json");
+  const key = 'platform-1.0.0"\n};\nglobalThis.compromised = true;';
+  const checksum = 'checksum"\\\nvalue';
+
+  try {
+    await updateChecksums(outputPath, [
+      { checksum, key },
+      { checksum: "duplicate", key },
+    ]);
+
+    const content = await fs.readFile(outputPath, "utf8");
+    expect(JSON.parse(content)).toEqual({ [key]: checksum });
+    expect(content.endsWith("\n")).toBe(true);
+  } finally {
+    await fs.rm(tempDirectory, { force: true, recursive: true });
+  }
+});