Pluggable support for Operators in Kubeapps

[ppbaena]

Summary
Create a plugin to provide support for operators in Kubeapps

Background and rationale
We've been working on plugin-based support for different packaging systems, moving across our initial Helm support as well as adding fluxv2 and Carvel support.

As Kubeapps provides support for operators (not by default), it would be interesting to add this support in a standard, pluggable way.

Description
Create a plugin to provide support for operators in Kubeapps, according to the new pluggable architecture and kubeapps-api.

Acceptance criteria
A new plugin including the following is available in Kubeapps:

• Design for the new plugin
• List available packages
  • GetAvailablePackageSummaries
  • GetAvailablePackageDetail
  • GetAvailablePackageVersions
• List installed packages
  • GetInstalledPackageSummaries
  • GetInstalledPackageDetail
• Action "buttons"
  • CreateInstalledPackage
  • UpdateInstalledPackage
  • DeleteInstalledPackage
• GetPackageRepositories
• Operators are listed together with other package formats in Kubeapps
• End-to-end tests are available for operators

Additional context
This is the parent issue with the proposal to provide pluggable support for operators. Any other issue/task created should be linked to this one.

[absoludity]

As Kubeapps provides support for operators (not by default), it would be interesting to add this support in a standard, pluggable way.

Not only interesting: the reason we don't enable the operator support by default is because to support the existing operator functionality, the dashboard relies on the insecure proxying of the k8s API, talking directly with the k8s API server. So enabling it currently exposes the k8s API server, possibly unintentionally by the installer.

[ppbaena]

Proposal for the design of the operators plugin added. Moved to backlog to re-prioritize it.