Update index generator to generate new index schema which supports multi versions

[yangcao77]

Please specify the area for this PR
index generator
registry build scripts
registry server

What does does this PR do / why we need it:
Update index generator to generate new index schema which supports multi versions.
Update registry build scripts to be able to read stack.yaml and new index schema for samples, to be able to fetch and cache stack/sample content in registry server.
Update existing registry server endpoint /index and /index/{type} to convert back to use old index schema before returning. update existing registry server endpoint devfiles/{name} to return devfile content of default version.

Which issue(s) this PR fixes:

Fixes devfile/api#761

PR acceptance criteria:

• Test (WIP)

• Documentation (WIP)

How to test changes / Special notes to the reviewer:
run ./build_registry.sh and deploy the built devfile-index image to cluster.
send GET request to server to test endpoints, exec into container to check generated index.json, and stack/sample directory contents.

[yangcao77]

Changes Examples:

• stacks/sample with multiple versions:

bash-4.4$ pwd
/registry/stacks/go
bash-4.4$ ls
1.1.0  1.2.0  stack.yaml

bash-4.4$ pwd
/registry/samples/code-with-quarkus
bash-4.4$ ls
1.0.0  1.1.0  quarkus_icon_rgb_default.svg  sampleName.zip

• new index schema content:

[
  {
    "name": "go",
    "displayName": "Go Runtime",
    "description": "Stack with the latest Go version",
    "type": "stack",
    "tags": [
      "Go",
      "testtag"
    ],
    "icon": "https://raw.githubusercontent.com/devfile-samples/devfile-stack-icons/main/golang.svg",
    "projectType": "go",
    "language": "go",
    "provider": "Red Hat",
    "versions": [
      {
        "version": "1.1.0",
        "schemaVersion": "2.0.0",
        "default": true,
        "description": "Stack with the latest Go version with devfile v2.0.0 schema verison",
        "tags": [
          "Go"
        ],
        "icon": "https://raw.githubusercontent.com/devfile-samples/devfile-stack-icons/main/golang.svg",
        "links": {
          "self": "devfile-catalog/go:1.1.0"
        },
        "resources": [
          "devfile.yaml"
        ],
        "starterProjects": [
          "go-starter"
        ]
      },
      {
        "version": "1.2.0",
        "schemaVersion": "2.1.0",
        "description": "Stack with the latest Go version with devfile v2.1.0 schema verison",
        "tags": [
          "testtag"
        ],
        "icon": "https://raw.githubusercontent.com/devfile-samples/devfile-stack-icons/main/golang.svg",
        "links": {
          "self": "devfile-catalog/go:1.2.0"
        },
        "resources": [
          "devfile.yaml"
        ],
        "starterProjects": [
          "go-starter"
        ]
      }
    ]
  },
  {
    "name": "code-with-quarkus",
    "displayName": "Basic Quarkus",
    "description": "A simple Hello World Java application using Quarkus",
    "type": "sample",
    "tags": [
      "Java",
      "Quarkus"
    ],
    "icon": "https://design.jboss.org/quarkus/logo/final/SVG/quarkus_icon_rgb_default.svg",
    "projectType": "quarkus",
    "language": "java",
    "versions": [
      {
        "version": "1.1.0",
        "schemaVersion": "2.2.0",
        "default": true,
        "git": {
          "remotes": {
            "origin": "https://github.com/devfile-samples/devfile-sample-code-with-quarkus.git"
          }
        },
        "description": "java quarkus with devfile v2.2.0"
      },
      {
        "version": "1.0.0",
        "schemaVersion": "2.0.0",
        "git": {
          "remotes": {
            "origin": "https://github.com/elsony/devfile-sample-code-with-quarkus.git"
          }
        },
        "description": "java quarkus with devfile v2.0.0"
      }
    ]
  },

• response from /index/all

[
  {
    "name": "go",
    "version": "1.1.0",
    "displayName": "Go Runtime",
    "description": "Stack with the latest Go version",
    "type": "stack",
    "tags": [
      "Go"
    ],
    "icon": "https://raw.githubusercontent.com/devfile-samples/devfile-stack-icons/main/golang.svg",
    "projectType": "go",
    "language": "go",
    "links": {
      "self": "devfile-catalog/go:1.1.0"
    },
    "resources": [
      "devfile.yaml"
    ],
    "starterProjects": [
      "go-starter"
    ],
    "provider": "Red Hat"
  },
    {
    "name": "code-with-quarkus",
    "displayName": "Basic Quarkus",
    "description": "A simple Hello World Java application using Quarkus",
    "type": "sample",
     "tags": [
      "Java",
      "Quarkus"
    ],
    "icon": "https://design.jboss.org/quarkus/logo/final/SVG/quarkus_icon_rgb_default.svg",
    "projectType": "quarkus",
    "language": "java",
    "git": {
      "remotes": {
        "origin": "https://github.com/devfile-samples/devfile-sample-code-with-quarkus.git"
      }
    }
  },

• response from /devfiles/{name}

[johnmcollier]

Looks good to me. Some nice changes in here and seems to work fine with odo too.

👍

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: johnmcollier, yangcao77

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