Decouple editor definitions from the plugin registry

[ibuziuk]

Is your task related to a problem? Please describe

Currently, plugin registry contains both plugins and editor definitions https://github.com/eclipse-che/che-plugin-registry
which breaks single-responsibility principle.
What is more even if internal plugin registry is not used e.g.

pluginRegistry:
      openVSXURL: "https://open-vsx.org/"

The operand is still there for hosting editor definitions - https://github.com/eclipse-che/che-plugin-registry/blob/main/che-editors.yaml

plugin-registry operand is running and consuming resources only for hosting a single yaml file

Describe the solution you'd like

use cm for editor definitions similar to #22429

Describe alternatives you've considered

let UD handle hosting of editor definitions

Additional context

No response

[ibuziuk]

Docs PR has not been merged yet - eclipse-che/che-docs#2738