Theia should be the default editor

[l0rd]

Description

When a user defines a Che 7 workspace (using a devfile, a workspace json or a stack) he needs to specify the editor. Otherwise, if no tools are defined, he gets the following error:

{
  "message": "Devfile schema validation failed. Error: /devfile object has missing required properties ([\"tools\"])"
}

and, if at least a tool is defined, the workspace is created but the execution fails (wsagent server doesn't exist):

Most of the users will only want to use the default editor (che-theia) and we should make it possible to use a devfile without a theia-editor and without tools.

In addition, if the editor is Theia, the exec-plugin should be loaded by default:

For instance a user should be able to use the following devfile

specVersion: 0.0.1
name: petclinic-dev-environment
projects:
  - name: petclinic
    source:
      type: git
      location: 'git@github.com:spring-projects/spring-petclinic.git'

and it should be equivalent to

---
specVersion: 0.0.1
name: petclinic-dev-environment
projects:
  - name: petclinic
    source:
      type: git
      location: 'git@github.com:spring-projects/spring-petclinic.git'
tools:
  - name: theia-editor
    type: cheEditor
    id: org.eclipse.che.editor.theia:1.0.0
  - name: exec-plugin
    type: chePlugin
    id: che-machine-exec-plugin:0.0.1

[benoitf]

@l0rd how to differentiate someone who really want no editor and someone that want the default in the devfile ?

[l0rd]

@benoitf I never thought about supporting workspace without editor. What that for?

Anyway I think that we can agree that most of users will want Theia hence it should be the default: if a user want an editor-free workspace he will need to specify it explicitly (e.g. with an attribute like editorFree: true or specifying a particular cheEditor with id: empty-editor).

[benoitf]

@l0rd let say I just want headless containers. Like deploying my application without the need to develop it :-)

[garagatyi]

What if user starts workspace for application deployment/check but develops in a desktop IDE and syncs files to the workspace? Seems like a case for a headless workspace.