feat(cli): Add a config command to manage the default settings

[essobedo]

fixes #1184

Motivation

If we don't want to execute the commands against the default namespace, we need to add the flag -n to all commands or use the command kubectl config set-context --current --namespace=<my-namespace> to set the default namespace at kubectl config level, but we would like to propose something out of the box in kamel cli

Modifications:

• Add a new command called config to set the default namespace and list the existing settings
• Allow to read and set the settings in the 4 supported locations
• Ensure that the namespace used is the one set in the configuration of the config command if any when no namespace has been specified in the command
• Add some doc about how to use it
• Fix the existing doc file-based-config.adoc

Release Note

feat(cli): Add a config command to manage the default settings

[tadayosi]

That's an awesome enhancement! To understand how this cmd intends to be used, could you provide some example usages? It'd be also great if you could add a section for the usages of the cmd here:
https://github.com/apache/camel-k/blob/main/docs/modules/ROOT/pages/cli/file-based-config.adoc

[squakez]

Nice work. However, some example on how to use the new command would be good to see how it works. Either as a documentation or as an additional comment to this PR.

[essobedo]

I've just added some doc hoping that it clarifies it a little bit more

[squakez]

LGTM. I'd make an additional effort to include an E2E test to make sure we won't break this feature in the future.

[essobedo]

LGTM. I'd make an additional effort to include an E2E test to make sure we won't break this feature in the future.

Do you mean that E2E tests are also expected even for pure client-side features? I mean the operator is not involved and it only manipulates local files on the client side that is why I proposed only unit tests. I have a test that checks the behavior too https://github.com/apache/camel-k/pull/3599/files#diff-4e0df340b8c06d6aa9b35d150ac8f92bd3581782cbe423209151170311ccbc6dR120-R137, do you still prefer to have an additional E2E test?

[squakez]

@essobedo yeah, I think we can test this as well. I think we can have this configuration file with default namespace created ad hoc from the test (instead of using the -n as we're doing for the other tests), then running an integration and verifying that this is running.

[tadayosi]

For E2E, this place should be ideal to put some config_test.go:
https://github.com/apache/camel-k/tree/main/e2e/namespace/install/cli

[squakez]

Great, looks good!