Add skeleton for code analytics

What does this MR do?

This MR adds Vue / Vuex skeleton for the new Code Analytics feature. It simply creates and mounts the Vue app that will later run under /-/analytics/code_analytics

This is behind the code_analytics feature flag introduced in !17618 (merged)

UX approval was provided here: !18272 (comment 228811137)

Code Analytics plan

The MR provides the foundation for the following plan

Screenshots

Desktop	Mobile

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines
• Style guides

Part of issue: #13008 (closed)