refactor(qa): split Matrix QA into optional plugin (#66723)

Merged via squash.

Prepared head SHA: 27241bd089
Co-authored-by: gumadeiras <5599352+gumadeiras@users.noreply.github.com>
Co-authored-by: gumadeiras <5599352+gumadeiras@users.noreply.github.com>
Reviewed-by: @gumadeiras

extensions/qa-matrix/src/cli.test.ts

@@ -0,0 +1,29 @@
+import { Command } from "commander";
+import { describe, expect, it } from "vitest";
+import { matrixQaCliRegistration } from "./cli.js";
+
+describe("matrix qa cli registration", () => {
+  it("keeps disposable Matrix lane flags focused", () => {
+    const qa = new Command();
+
+    matrixQaCliRegistration.register(qa);
+
+    const matrix = qa.commands.find((command) => command.name() === "matrix");
+    const optionNames = matrix?.options.map((option) => option.long) ?? [];
+
+    expect(optionNames).toEqual(
+      expect.arrayContaining([
+        "--repo-root",
+        "--output-dir",
+        "--provider-mode",
+        "--model",
+        "--alt-model",
+        "--scenario",
+        "--fast",
+        "--sut-account",
+      ]),
+    );
+    expect(optionNames).not.toContain("--credential-source");
+    expect(optionNames).not.toContain("--credential-role");
+  });
+});