chore: add devfile.yaml to work with plugin registry

[svor]

What does this PR do?

Introduces devfile.yaml with commands that allow to verify changes made in the plugin registry.

It is important to have an access to modify CheCluster definition on OS cluster

Only one extension in the list of the embedded plugin registry:

Rresult of the changes:

Related issue: eclipse-che/che#22243

[nickboldt]

+1 if nothing broke while testing.

I figure if you use that flag, ownership will change to root when built during Brew builds, and if you do so inside DS via devfile, it'll change to whatever value is allowed by non-root container's openshift user.