Devfile registry support for Devfile v2 zip files

[l0rd]

Is your enhancement related to a problem? Please describe

Devfile v2 are specified using the link.v2 field in meta.yaml:

---
displayName: Go
description: Stack with Go 1.14
tags: ["Debian", "Go"]
icon: /images/go.svg
links:
  v2: https://github.com/che-samples/golang-echo-example/tree/devfile2

The link.v2 URL points to a git repository that includes a devfile (devfiles are not included in the devfile registry anymore).

In the case of zip files what should be the value of link.v2? Where is the devfile stored?

Describe the solution you'd like

There are 2 alternatives:

Alternative n1: Include v2 devfile DevWorkspace files in the devfile registry

At registry build time we should:

• extract the devfile.yaml, .vscode/extensions.json and .che/che-theia-plugins.yaml from the git repo
• export the git repository as a zip file
• generate a devfilev2.yaml DevWorkspace and DevWorkspaceTemplates yaml files from the .vscode/extensions.json, .che/che-theia-plugins.yaml
• include the DevWorkspace and DevWorkspaceTemplates yaml files in the stack folder
• update the meta.yaml

generatedDevWorkspaceFiles:
  path: ./DevWorkspaceFiles/

Alternative n2: Include a git server in the devfile registry

• clone the sample in some devfile-registry folders
• expose these git repositories through gitweb
• Update v2 links URLs with the devfile registry URL in entrypoint
  --> Need to add a gitweb URL provider/resolver to handle it properly (protocol could be used with something like gitweb://<host>/repository-name )

[benoitf]

we could as well implement #19718 to have DevWorkspace templates instead of inlining everything into the devfile so we'll avoid other processing time at runtime

[svor]

We are going to start with #19718 to provide Dev Workspace templates for che-theia editor and host them in the devfile registry

[l0rd]

Updated the description to use DevWorkspace yaml files instead of devfile

[svor]

We finished work to pre-build DevWorkspace templates for devfile v2 in devfile registry #19718. But this templates don't have projects section which references on zip file. Currently we are working on it.

To support AirGap scenarios, the final step should be done on the dashboard side to apply generated DevWorspace objects from the registry: Use generated DevWorkspaceTemplates from the devfile registry to create workspaces

cc @l0rd @ibuziuk