Add cleanUrls option to CLI interface

[joeuy]

Description

Currently cleanUrls is only configurable via a specific config file. I am suggesting and would be happy to send PR to add a CLI option to control cleanUrls. Very similar change to --no-request-logging https://github.com/vercel/serve/pull/716/files

Why

Currently cleanUrls is only configurable via a specific config file. Creating a configuration file just for this option could cause confusion/maintenance hassle as people don't know the file path to config should be specified relative to the public folder.

Additional it seems odd that some options are configurable via CLI and others are not.

Example issues people are facing: https://github.com/vercel/serve/issues/732 and https://github.com/vercel/serve/issues/722

Alternatives

1. create a config file.
2. add --config CLI argument, and make sure path is correct to each public folder being served.