✨ Add support to scaffold controllers for External Types

[camilamacedo86]

Introduces the option to allow users scaffold controllers for external types by running:

Example

kubebuilder create api --group certmanager --version v1 --kind Certificate --controller=true --resource=false --make=false --external-api-path=github.com/cert-manager/cert-manager/pkg/apis/certmanager/v1 --external-api-domain=cert-manager.io

Partial Close: #1999
We need to either add the support for Core and External types for webhooks which is blocked by: #4150

[camilamacedo86]

Hi @fischor, @sundaram2021,

See the changes here.

We need to add the support for controllers first, ensure the docs, change in the PROJECT config and re-scaffold helper first for then we be able to work on with those sample supports for webhooks in a follow up.

So, please feel free to help us in the review of this one for we are able to looking for in the next step.

[camilamacedo86]

Hi

@hardikdr, @kopiczko, @janik-io, @oliviermichaelis, @ctrought, @armsnyder, @samuelvl, @allenhaozi, @wangjiusi

I know that you were looking for that.
The follow up here is add the same to the webhooks.
But we need to move forward step by step and we have another PR that blocks us to
do the changes in the webhooks at the moment.

So, if you be able to help us with reviews that will be great.

[camilamacedo86]

Hi @fischor,

See that we have a flag for the domain now and the new makers to scaffold the checks we can add/discuss in a follow so that we can shape those better and make easier the review. (We can describe the behaviour without to demo why that is required/recommended and etc)

Thank you for your time on reviews.
Fell free to check it now.

[fischor]

LGTM. Just some minors left in the docs.

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[camilamacedo86]

Hi @fischor

Thank you a lot for your time and help with the review. 🥇
The latest NITs are not either addressed !

[camilamacedo86]

c/c @lingdie

[camilamacedo86]

I think you all have been looking for that:
@hardikdr, @kopiczko, @janik-io, @oliviermichaelis, @ctrought, @armsnyder, @samuelvl, @allenhaozi, @wangjiusi