feat: automatically link site post creation

[ximenasandoval]

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Summary

Fixes #3827

When running the command netlify sites:create the CLI returns a success message with Admin URL, URL and Site ID. If we try to run netlify build we get an error "Could not find site ID. Please run netlify link".

This change runs link after creating a site, as well as adding a flag --disable-linking to sites:create if we want to avoid linking the current directory.

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[lukasholzer]

Sorry for the late review but we where discussing this issue internally. But I think this solution should work pretty fine!

I tested it out and it is a way better DX.

Thanks for your effort and adding the tests 😍 I appreciate this a lot!

@erezrokah would it be a breaking change? As we change the behaviour of the existing link command or can it be seen as feature. Not sure if someone relies on the behaviour of NOT linking the site

[lukasholzer]

Can you please elaborate why you have changed this behaviour?

the exit should be the same behaviour.
IMHO early exits are easier to read then else if statements.

[ximenasandoval]

Sure! I removed exit because the sites-create tests were failing since it was calling exit even if everything was okay and made the test fail. By removing the exit function I needed to make sure the other paths of the link command weren't being executed, so I added the else if to the conditions 😅

[lukasholzer]

In general I would try to not change the code because of tests.
As the exit function could be mocked in the tests and checked if it would be called.

But this is fine in this case