Apply Prettier to the entire project

This ensures that our tests will be formatted by Prettier, among other things.

.eslintrc.cjs

@@ -1,42 +1,34 @@
 module.exports = {
-    plugins: [
-        "matrix-org",
-    ],
-    extends: [
+  plugins: ["matrix-org"],
+  extends: ["plugin:matrix-org/react", "plugin:matrix-org/a11y", "prettier"],
+  env: {
+    browser: true,
+    node: true,
+  },
+  parserOptions: {
+    ecmaVersion: "latest",
+    sourceType: "module",
+  },
+  rules: {
+    "jsx-a11y/media-has-caption": ["off"],
+  },
+  overrides: [
+    {
+      files: ["src/**/*.{ts,tsx}"],
+      extends: [
+        "plugin:matrix-org/typescript",
         "plugin:matrix-org/react",
-        "plugin:matrix-org/a11y",
         "prettier",
-    ],
-    env: {
-        browser: true,
-        node: true,
+      ],
+      rules: {
+        // We're aiming to convert this code to strict mode
+        "@typescript-eslint/no-non-null-assertion": "off",
+      },
     },
-    parserOptions: {
-        "ecmaVersion": "latest",
-        "sourceType": "module",
-    },
-    rules: {
-        "jsx-a11y/media-has-caption": ["off"],
-    },
-    overrides: [
-        {
-            files: [
-                "src/**/*.{ts,tsx}",
-            ],
-            extends: [
-                "plugin:matrix-org/typescript",
-                "plugin:matrix-org/react",
-                "prettier",
-            ],
-            rules: {
-                // We're aiming to convert this code to strict mode
-                "@typescript-eslint/no-non-null-assertion": "off",
-            },
-        },
-    ],
-    settings: {
-        react: {
-            version: "detect",
-        },
+  ],
+  settings: {
+    react: {
+      version: "detect",
     },
+  },
 };