Make port and dir flag available

[otofune]

- Summary

Same as title.

• Fix type of 'dir' option
• Use flags.dir / flags.port in application

I wanted to change port & dir. I found its option in netlify cli, but it didn't works.

- Test plan

0. Use --dir= and --port= option in your local environment without netlify.toml.
1. With --dir= option, it's successful if you can't see the message from L198.
2. WIth --port= option, it's successful if you can see Server now ready on http://localhost:${your port} message.

- Description for the changelog

Make port and dir flag available

- A picture of a cute animal (not mandatory but encouraged)

[mikhuang]

This is very cool and very useful. However, this doesn't seem to work when both command and dir are set. I had to alter the object sent to serverSettings on line 187 as follows:

let settings = await serverSettings(Object.assign({}, config.dev, {
      command: flags.command,
      port: flags.port,
      functions: flags.functions,
      publish: flags.dir,
    }));

[jack-sf]

@sw-yx can we merge this? ;) This looks very good.

[swyxio]

i dont maintain netlify dev anymore. @RaeesBhatti

[otofune]

#205