quic: set up FunctionTemplates more cleanly

- Use `kInternalFieldCount`, similar to 0fac393d.
- Always inherit from the correct parent template, similar to 8a7201b2.
- Always provide a template class name.

PR-URL: https://github.com/nodejs/node/pull/33968


Reviewed-By: James M Snell <jasnell@gmail.com>