BREAKING CHANGE(config): Remove all options but legacy and webauthn from auth-type

[darcyclarke]

Summary

The current set of options for auth-type has numerous values which overlap (ex. legacy, sso, saml, oauth). Because of how the CLI expects the registry to handle authentication, it is essentially the server's job to interpret & request follow-up information from the end-user. The CLI handles prompts for step-up & MFA prompts utilizing a forward-looking polling strategy. With the introduction of web, there should only be two potential values for auth-type moving forward (legacy & web). If users have previously been defining sso, saml or oauth we should be directing them to using legacy.

Bike Shedding / Questions

• Do we want to change the name of the default value since it now is expected to be more all-encompassing? (ex. should legacy be changed to something like default)

Actions

• remove unnecessary sso, saml & oauth configurations & code
• discuss naming of the legacy config value with team & at an RFC call
• pull the code leftover in cli/lib/auth/legacy.js (ref. https://github.com/npm/cli/blob/f9abee79abe541226a249f50bdeec41317dd5712/lib/auth/legacy.js) into npm-profile

Links & References

• https://github.com/npm/cli/blob/f9abee79abe541226a249f50bdeec41317dd5712/lib/auth/sso.js#L1-L8
• https://github.com/npm/cli/blob/f9abee79abe541226a249f50bdeec41317dd5712/docs/content/commands/npm-adduser.md#L93