feat: Add ability to manage extensions installation using a ConfigMap

[RomanNikitenko]

What does this PR do?

• Adds ability to manage extensions installation using vscode-editor-configurations ConfigMap
• Install button is disabled and there is a warning message if an extension is not allowed for installation

• It's possible to check allowed extensions list using Settings => extensions.allowed key:

- Installed extension will be disabled when administrator adds it to not allowed extensions:

Examples of the different extensions.allowed setting values:

What issues does this PR fix?

https://issues.redhat.com/browse/CRW-8866
see another part for the issue ^ in #617

How to test this PR?

• there are different use cases for testing - click any item to expand a use case details
• each use case contains example of the policy.json section
• add the corresponding policy.json section to the vscode-editor-configurations ConfigMap, see https://eclipse.dev/che/docs/stable/administration-guide/editor-configurations-for-microsoft-visual-studio-code/
• restarting a workspace is required to apply the ConfigMap changes

1. Deny All Extensions

policy.json: |
    {
      "AllowedExtensions": { 
          "*": false
       }
    }

Expected behavior:

Extension	Can be installed
All extensions	-

2. Only extensions defined in the "AllowedExtensions" section can be installed

policy.json: |
    {
      "AllowedExtensions": { 
          "dbaeumer.vscode-eslint": true,
          "redhat.vscode-yaml": true
       }
    }

Expected behavior:

Extension	Can be installed
dbaeumer.vscode-eslint	+
redhat.vscode-yaml	+
other extensions	-

3. Defined extensions can not be installed, all other extensions are allowed

policy.json: |
    {
      "AllowedExtensions": { 
          "*": true,
          "dbaeumer.vscode-eslint": false,
          "redhat.vscode-yaml": false
       }
    }

Expected behavior:

Extension	Can be installed
dbaeumer.vscode-eslint	-
redhat.vscode-yaml	-
other extensions	+

4. Do not allow all extensions from a specific publisher (by publisher ID)

policy.json: |
    {
      "AllowedExtensions": { 
          "*": true,
          "redhat": false
       }
    }

Expected behavior:

Extension	Can be installed
all redhat extensions	-
redhat.java	-
redhat.vscode-xml	-
redhat.vscode-yaml	-
redhat.vscode-quarkus	-
other extensions	+

5. Allow only extensions from a specific publisher (by publisher ID), other extensions are not allowed

policy.json: |
    {
      "AllowedExtensions": { 
          "*": false,
          "redhat": true
       }
    }

Expected behavior:

Extension	Can be installed
all redhat extensions	+
redhat.java	+
redhat.vscode-xml	+
redhat.vscode-yaml	+
redhat.vscode-quarkus	+
other extensions	-

6. Allow only specified versions of an extension

policy.json: |
    {
      "AllowedExtensions": { 
          "*": true,
          "redhat.vscode-xml": ["0.28.0", "0.28.1"]
       }
    }

Expected behavior:

Extension	Can be installed
all redhat extensions	+
0.28.0 redhat.vscode-xml	+
0.28.1 redhat.vscode-xml	+
another version of redhat.vscode-xml	-
other extensions	+

Does this PR contain changes that override default upstream Code-OSS behavior?

• the PR contains changes in the code folder (you can skip it if your changes are placed in a che extension )
• the corresponding items were added to the CHANGELOG.md file
• rules for automatic git rebase were added to the .rebase folder

[github-actions]

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Pull Request images published ✨

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Pull Request images published ✨

Editor amd64: quay.io/che-incubator-pull-requests/che-code:pr-605-amd64
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[github-actions]

Pull Request images published ✨

Editor amd64: quay.io/che-incubator-pull-requests/che-code:pr-605-amd64
Editor arm64: quay.io/che-incubator-pull-requests/che-code:pr-605-arm64
Dev image: quay.io/che-incubator-pull-requests/che-code-dev:pr-605-dev-amd64