Code suggestions: show walkthrough when group admin enables the feature for the first time

Background

We will be launching AI assisted code suggestions as a pre-installed extension in the GitLab web IDE in May. This issue is part of an epic for the UX portion of this project.

Context

• The code suggestions feature will come as a pre-installed (@built-in) extension as part of the GitLab Web IDE.
• The extension is disabled by default.
• The group admin must enable the extension in GitLab before the user can use code suggestions (https://gitlab.com/gitlab-org/gitlab-web-ide/-/issues/124).
• Until the group admin has enabled the feature, the user will see code suggestions in the IDE but not be able to use it
• When the group admin enables the feature for the first time, it would be great to inform the user that the feature is now available to use by showing a walkthrough.

Flow

Description	Image
User cannot access the feature because group admin has not yet enabled it (#125 (moved))
User opens IDE after group admin has enabled code suggestions for the first time

Figma file (under first enablement section)

Considerations

• The walkthrough should only be shown on the first enablement. We should note down if the user has seen the walkthrough somehow. For example, if they enable the extension on a different device later, they should not see the walkthrough.

Content of walkthrough

I've roughly mocked up some content to start the conversation. For ease of collaboration I've created a google doc to work out the content.