Build workspace base image and use it as base for other workspace images

Everyone can contribute. Help move this issue forward while earning points, leveling up and collecting rewards.

• Collaborate/take over this issue

MR - Add workspace base image (gitlab-build-images!983 - merged)

MR - Update workspace web ide image to use workspace... (gitlab-build-images!994 - merged)

MR - Update to use latest workspace image (gitlab-web-ide!556 - merged)

MR - chore(workspace): update to latest workspace ba... (gitlab-vscode-extension!2804 - merged)

Description

Based on our discussions here, gitlab-build-images!912 (comment 2384999039), we would like to create a workspace base image that only contains workspace specific changes(e.g. creating new user with right permissions) ad mise.

Then other workspace images could be built on top of this workspace base image, for example WebIDE Workspace image, and Workspace default image.

One thing to consider is when using build_dynamic_image job does not take custom image as base, so we might want to extend it to accept one custom base.

Acceptance criteria

• Build and publish workspace base image from Ubuntu, with only mise and workspace specific changes(e.g. creating new user with right permissions)
• Update workspace default image, and workspace web ide image to use the workspace base image
• Also update web-ide and vscode extension repos to use mise, and also update from init script to postStart hook
• Install sshd
• Ensure gitlab-workspaces user is created as userid 5001

Implementation plan

NA