Allow the CLI to login to free/trial workspaces for Bolt Developers

[vegeris]

Description

Logging in to the CLI has been blocked on free/trial teams since the days where the CLI was only used for ROSI apps since Slack-hosted apps require a paid workspace, but now the CLI is used by Bolt developers a well.

Requirements

• I've read and understood the Contributing guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've searched for any related issues and avoided creating a duplicate issue.

[haidargit]

Hello @zimeg, @vegeris, and slack team 👋🏻
I’m interested in opening a PR for this case, but before that, i’m looking for some feedback on this.

is there a specific flag we can add to slack's current generateAuthTicket request (internal/api/auth.go) so that Slack knows of Bolt developer status, then we may bypass the paid workspace check?

or how about pointing to a different auth endpoint, is that suitable?

we can also add a fallback message. If the block is still active on Slack's end, maybe we can just catch the error. we could show a prompt guiding users on free/trial workspaces to log in using the --token xoxp-... flag instead.

That’s just my take, but i think there’s a better way to implement this case. What’s your take on the current cli state? 😃