Re-enable prettier for compiler/

Now that the compiler directory has its own prettier config, we can
remove the prettierignore entry for compiler/ so it still runs in your
editor if you open the root directory

ghstack-source-id: 5e3bd597cf2f11a9931f084eb909ffd81ebdca81
Pull Request resolved: https://github.com/facebook/react/pull/29993

.prettierignore

@@ -1,6 +1,5 @@
 build
 
-compiler
 packages/react-devtools-core/dist
 packages/react-devtools-extensions/chrome/build
 packages/react-devtools-extensions/firefox/build

scripts/prettier/index.js

@@ -55,6 +55,7 @@ const files = glob
     ignore: [
       '**/node_modules/**',
       '**/cjs/**',
+      'compiler/**',
       ...ignoredPathsListedInPrettierIgnoreInGlobFormat,
     ],
   })