title: How to load a .proto file in protoregistry
body: <p>I need to simply load the contents of a few <code>.proto</code> files directly as descriptor so I can manipulate them via reflection as per <a href="https://pkg.go.dev/google.golang.org/protobuf/reflect/protoregistry" rel="nofollow noreferrer">https://pkg.go.dev/google.golang.org/protobuf/reflect/protoregistry</a></p>
  <p>From what I can gather, I need to</p>
  <ol>
  <li>Load the contents of the file as a string.</li>
  <li>Use <code>prototext</code> to Unmarshal the string into a <code>descriptorpb.FileDescriptorProto</code></li>
  <li>Initialize a <code>ProtoFileDescriptor</code> with that</li>
  <li>Finally I can register the ProtoFileDescriptor in a registry.</li>
  </ol>
  <p>Do I really need to jump through all of these hoops, or am I completely missing another API?</p>