Check extensions of VS Code extension pack are running smoothly

[benoitf]

Is your task related to a problem? Please describe.

#15272 would bring support of Extension pack
But each extension should be running properly when support will be there.
This issue is to ensure that all API/features are available in Che-Theia to make sure that these extensions are running properly.

Describe the solution you'd like

Check that all extensions of the packs are able to run smoothly on Eclipse Che.
It includes:

• Git Extension pack: https://marketplace.visualstudio.com/items?itemName=donjayamanne.git-extension-pack
• Java Extension pack: https://marketplace.visualstudio.com/items?itemName=vscjava.vscode-java-pack
• Php Extension pack: https://marketplace.visualstudio.com/items?itemName=felixfbecker.php-pack
• Python Extension pack: https://marketplace.visualstudio.com/items?itemName=donjayamanne.python-extension-pack
• NodeJS pack: https://marketplace.visualstudio.com/items?itemName=waderyan.nodejs-extension-pack

Of course, some "non-open-source" extensions shouldn't be checked

Additional context

As it's for test/checking if it's working, all extensions can be used in a single Che plugin meta.yaml.

[che-bot]

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Mark the issue as fresh with /remove-lifecycle stale in a new comment.

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Moderators: Add lifecycle/frozen label to avoid stale mode.