fix: Allow generating SDKs locally without Fern token

[NathanFlurry]

Using Fern in an open source repo can be tricky since outside contributors currently need to have their own Fern token.

The fern generate --local does not require a Fern token to function. This PR disables prompting the user to sign in when using the local Docker generation.

[zdunecki]

Hi,

Any update on this? I see it's one of the factors that may help to run fern locally without any token/login required.

Best

[Amenocy]

is there any update regarding this pr?! it would be useful to merge it :)