Add Site related subcommands

[gugahoi]

This PR adds 3 new commands:

• sites list
• sites get [id]
• sites publish [id]
• sites domains [id]

All related to managing Webflow sites. It also adds a "failed request" check that I somehow overlooked.

[Nevvulo]

Overall looks good to me, just left some minor comments

[anonimitoraf]

It'd be nice to print the response result to make it clear that the cmd finished successfully

[gugahoi]

The response is "queued": true which is not particularly helpful in my opinion so thought silence was better.

[anonimitoraf]

Oh ok, yea that's not a big deal. Alternatively I was thinking of some generic message that says: "Published successfully"

[gugahoi]

But it might not have tho. The command was sent successfully and as per unix philosophy I think if there is no additional information, then the exit code should be enough to indicate if the action was successful.

[anonimitoraf]

Ah ok, queued != published. Fair enough

[anonimitoraf]

LGTM - I like the fact that commands targeting the same resource are all together