Add user tracking for visualization designer

Problem to solve

As a Product Analytics team member I want to know if changes we make to Visualization Designer impact usage of the feature, so I can revert/continue as needed.

Proposal

Track the following events using GitLab's internal event tracking:

• Count of users who visit designer
• Count of users who save a visualization
• Count of users who edit a visualization Moved to #385884 (closed)
• Count of projects that have a saved visualization Moved to Add project tracking for visualization designer (#431157)

Measure of success / Acceptance Criteria

• A chart can be built of the data in Sisense/Tableau
• A visualization can be built in Product Analytics (pending custom events being parsable)

Implementation plan

frontend weight 2️⃣

Use internal event tracking to count the following events:

Tracking	Event_ID (suggestion)	Tracking location
User views designer	user_viewed_custom_dashboard_visualization_designer	frontend
User creates a visualization	user_created_custom_dashboard_visualization	frontend
Project has a visualization	visualization_saved_on_project	?