Add end tutorial button to learn gitlab

What does this MR do and why?

What

Add an End tutorial button to Learn GitLab

• Adds an end tutorial button to learn gitlab
• Adds new ended column to onboarding_progress table

Why

The Learn GitLab page is always shown to users after it has been created in a project. This has become a point of frustration as users cannot hide this page or remove it from their navigation sidebar.

DB Query Plan

https://console.postgres.ai/gitlab/gitlab-production-main/sessions/30750/commands/95509

 Index Scan using index_onboarding_progresses_on_namespace_id on public.onboarding_progresses  (cost=0.43..3.45 rows=1 width=256) (actual time=0.050..0.051 rows=0 loops=1)
   Index Cond: (onboarding_progresses.namespace_id = 9970)
   Filter: (onboarding_progresses.ended_at IS NULL)
   Rows Removed by Filter: 0
   Buffers: shared hit=6
   I/O Timings: read=0.000 write=0.000

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

How to set up and validate locally

1. Create a new group and project
2. Observe the learn gitlab page
3. Press the End tutorial button

Related to #354039 (closed)