Supports closed set of extensions in the WebIDE
<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=469030) </details> <!--IssueSummary end--> ### Proposal When using the WebIDE, it would be very useful to support the "auto-installation" of a predefined set of extensions. Leveraging the usage of the [recommended extensions](https://code.visualstudio.com/docs/editor/extension-marketplace#_workspace-recommended-extensions), and ensuring that only the recommendations are installed (automatically) and that all unwantedRecommendations are automatically removed. This helps companies to provide a default setup, matching their constraints, for any project. <!-- Label reminders Use the following resources to find the appropriate labels: - Use only one tier label choosing the lowest tier this is intended for - https://gitlab.com/gitlab-org/gitlab/-/labels - https://about.gitlab.com/handbook/product/categories/features/ -->
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