Call 404 handler if requested path is a dotfile

[GormanFletcher]

This closes #218 and #219. The registered notFoundHandler wasn't being called when the request path included dotfiles with send's default configuration of ignoring dotfiles. Previous behavior resulted in fastify printing an exception and leaving the request hanging.

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

[mcollina]

lgtm