Resolve "[FE] Visually depict Value Stream Analytics stages as a flow"

What does this MR do?

This MR adds the path component to the Value Stream Analytics page. It does this behind a new feature flag; value_stream_analytics_path_navigation

Screenshots

Feature flag disabled	Desktop	Mobile
	Screen_Recording_2020-05-11_at_15.06.28	Screen_Recording_2020-05-11_at_15.07.27

Testing locally will result in incorrect background path icon colors until !31591 (merged) is merged.

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry (Not adding - behind FF)
• Documentation (if required)
• Code review guidelines
• [-] Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content

Availability and Testing

• [-] Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team

Related issue

#213905 (closed)