pkg/cli: use cmd error idiom for 'init' and plugin keys in cmd errors

[estroz]

Instead of only using plugin names in command errors, keys should be used for more informative error messages. An action should be suggested in the error message as well.

Additionally, the init command setup should use the cmdErr idiom used by other command setups for uniform error reporting.

/cc @camilamacedo86 @joelanford @mengqiy

[estroz]

/test pull-kubebuilder-e2e-k8s-1-16-2

[camilamacedo86]

IMO this error should NOT occur at all. Note that c.resolvedPlugins will return all supported plugins for the PROJECT version which can be, for example: go.kubebuilder.io/v3.0.0, go.kubebuilder.io/v3.1.0, go.kubebuilder.io/v3.2.0

Then, I understand that was defined that we should use the upper version in this scenario.

Note that the issue is NOT faced at the moment by the CI because KB has just 1 plugin version implemented currently. But the Issue is tracked in #1526.

[estroz]

@camilamacedo86 which error are you talking about, the duplicate error or not-found error? The duplicate error will happen if a user specifies an ambiguous key that doesn't correspond to a default plugin. The not-found error will happen if a user specifies a key that doesn't correspond to an existing plugin.

[camilamacedo86]

After our chat, I am ok with move forward with it.
It is
/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: camilamacedo86, estroz

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [camilamacedo86]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment