Deprecate functionality that is now in imgpkg

[joaopapereira]

Describe the problem/challenge you have
Some of the functionality that already is part of imgpkg should be deprecated from kbld

Describe the solution you'd like
Scenario 1:

Given I have kbld installed
When I execute kbld --help
Then I should not see reference to relocate, package or unpackage

Scenario 2:

Given I have kbld installed
When I execute kbld relocate --help
Then I should see

Command "relocate" is deprecated, please use 'imgpkg copy', learn more in https://carvel.dev/imgpkg/docs/latest/commands/#copy

Scenario 3:

Given I have kbld installed
When I execute kbld package --help
Then I should see

Command "package" is deprecated, please use 'imgpkg push', learn more in https://carvel.dev/imgpkg/docs/latest/commands/#push

Scenario 4:

Given I have kbld installed
When I execute kbld unpackage --help
Then I should see

Command "unpackage" is deprecated, please use 'imgpkg pull', learn more in https://carvel.dev/imgpkg/docs/latest/commands/#pull

Scenario 5:

Given I access https://carvel.dev/kbld
When I click on the Packaging & Relocation link
Then I should see

Packaging and Relocation

This functionality was deprecated in `kbld` and will be removed in the near future. Check the new tool [imgpkg](https://carvel.dev/imgpkg).

Anything else you would like to add:
In this initial story, we should hide the commands and in the future remove them

[cppforlife]

i wonder if it's also worth hiding pkg/unpkg/relocate commands from kbld -h? if not then may be also adding [deprecated] prefix to command description.

[danielhelfand]

I am wondering if it would be worthwhile to write a message to stderr with a deprecation warning. Maybe also mentioning imgpkg docs in the message. This would be in addition to hiding the commands from help.

Do we have any recommended time line for fully removing commands from other Carvel tools?

[joaopapereira]

I am wondering if it would be worthwhile to write a message to stderr with a deprecation warning. Maybe also mentioning imgpkg docs in the message. This would be in addition to hiding the commands from help.

Hmmm, I think we get that for free if we set the cobra command as deprecated, using the deprecated field in the struct. But it is good to ensure that.

Do we have any recommended time line for fully removing commands from other Carvel tools?

According to our release process document, we say 3 minor releases but we did not have a major discussion to understand if this timing makes sense to our type of tools that are more long living

[joaopapereira]

Fixed in both PRs associated

[joaopapereira]

This will be released on version v0.30.0