[CLI] Add --debug/--no-debug flag to quart run

[princerb]

This PR brings Quart's CLI in line with Flask's by exposing an explicit --debug/--no-debug option on the quart run command.

Usage: quart run [OPTIONS]

  Run a local development server.

Options:
  --debug / --no-debug     Set 'app.debug' separately from '--env'.
  -h, --host TEXT          The interface to bind to.
  -p, --port INTEGER       The port to bind to.
  --certfile, --cert FILE  Specify a certificate file to use HTTPS.
  --keyfile, --key FILE    The key file to use when specifying a certificate.
  --reload / --no-reload   Enable or disable the reloader
  --help                   Show this message and exit.

Tests added.

fixes #354

[pgjones]

Thanks, merged manually as 5f90c1c