[WIP] Devfile initial model, converters & schema

[mshaposhnik]

What does this PR do?

Initial implementation proposal for DevFile local part -- model, converter, REST & JSON schema prototype.

What issues does this PR fix or reference?

#11832

Docs PR

N/A

Yaml example:

version: 0.0.1
name: petclinic-dev-environment
projects:
  - name: petclinic
    source:
      type: git
      location: 'git@github.com:spring-projects/spring-petclinic.git'
tools:
  - name: mvn-stack
    type: chePlugin
    id: eclipse/maven-jdk8:1.0.0
  - name: theia-ide
    type: cheEditor
    id: eclipse/theia:0.0.3
  - name: jdt.ls
    type: chePlugin
    id: eclipse/theia-jdtls:0.0.3
commands:
  - name: build
    actions:
      - type: exec
        tool: mvn-stack
        command: mvn package
        workdir: /projects/spring-petclinic
  - name: run
    attributes:
      runType: sequential
    actions:
      - type: exec
        tool: mvn-stack
        command: mvn spring-boot:run
        workdir: /projects/spring-petclinic
  - name: other
    actions:
      - type: exec
        tool: jdt.ls
        command: run.sh

WS config after conversion example:

{
  "projects": [
    {
       "source": {
        "location": "git@github.com:spring-projects/spring-petclinic.git",
        "type": "git",
        "parameters": {}
      },
      "mixins": [],
      "name": "petclinic",
      "path": "/petclinic",
      "attributes": {}
    }
  ],
  "commands": [
    {
      "commandLine": "mvn package",
      "name": "build:mvn-stack",
      "type": "exec",
      "attributes": {
        "pluginId": "eclipse/maven-jdk8:1.0.0",
        "workingDir": "/projects/spring-petclinic"
      }
    },
    {
      "commandLine": "mvn spring-boot:run",
      "name": "run:mvn-stack",
      "type": "exec",
      "attributes": {
        "pluginId": "eclipse/maven-jdk8:1.0.0",
        "runType": "sequential",
        "workingDir": "/projects/spring-petclinic"
      }
    },
    {
      "commandLine": "run.sh",
      "name": "other:jdt.ls",
      "type": "exec",
      "attributes": {
        "pluginId": "eclipse/theia-jdtls:0.0.3"
      }
    }
  ],
  "environments": {
    "default": {
      "recipe": {
        "type": "dockerimage",
        "content": "eclipse/ubuntu_jdk8"
      },
      "machines": {
        "dev-machine": {
          "installers": [],
          "servers": {},
          "env": {},
          "volumes": {},
          "attributes": {
            "memoryLimitBytes": "2147483648"
          }
        }
      }
    }
  },
  "defaultEnv": "default",
  "name": "petclinic-dev-environment",
  "attributes": {
    "eclipse/maven-jdk8:1.0.0": "mvn-stack",
    "editor": "eclipse/theia:0.0.3",
    "eclipse/theia-jdtls:0.0.3": "jdt.ls",
    "plugins": "eclipse/maven-jdk8:1.0.0,eclipse/theia-jdtls:0.0.3",
    "eclipse/theia:0.0.3": "theia-ide"
  }
}