cmd/info: Support for multiple indexes

[ahmetb]

Somewhat breaking change. krew info now looks up ONLY available plugins
(no more looking at installed plugin receipts). The supported syntaxes are:

kubectl krew info NAME # assumes 'default'
kubectl krew info INDEX/NAME

With this change, info cmd will no longer work with plugins installed via
--manifest (as we won't be looking at installation receipts anymore).

/area multi-index
/assign @corneliusweig
cc: @chriskim06
Related issue: #483
fixes #559

[k8s-ci-robot]

@ahmetb: GitHub didn't allow me to assign the following users: corneliuseweig.

Note that only kubernetes-sigs members, repo collaborators and people who have commented on this issue/PR can be assigned. Additionally, issues/PRs can only have 10 assignees at the same time.
For more information please see the contributor guide

In response to this:

Somewhat breaking change. krew info now looks up ONLY available plugins
(no more looking at installed plugin receipts). The supported syntaxes are:

kubectl krew info NAME # assumes 'default'
kubectl krew info INDEX/NAME

With this change, info cmd will no longer work with plugins installed via
--manifest (as we won't be looking at installation receipts anymore).

/area multi-index
/assign @corneliuseweig
cc: @chriskim06
Related issue: #483

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[corneliusweig]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ahmetb, corneliusweig

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 [ahmetb,corneliusweig]

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