[VSA][FE] Introduce a default value stream

What does this MR do?

As part of our migration to bring UI and feature parity to project and group value stream analytics, we need to introduce the concept of a value stream to project level vsa. Previously project VSA worked on the assumption of only a single value stream being available, but we will eventually want to allow users to access multiple value streams similar to what is currently available at the group level.

The new endpoints are of the form:

• /(project-full-path)/-/analytics/value_stream_analytics/value_streams
• /(project-full-path)/-/analytics/value_stream_analytics/value_streams/default/stages

This MR:

• Adds a request for a default value stream to project VSA
• Adds a new request to fetch the value stream stages from the backend, replacing the hard coded stages
• Adds a new module for project VSA api requests
• Updates related specs

NOTE: there are lots of improvements that could be made to the templates, but they will mostly be replaced in %14.1 and provide no worse experience than we currently have.

Testing

Navigate to project level value stream analytics and the page should load, for example: http://gdk.test:3001/gitlab-org/gitlab-shell/-/value_stream_analytics

If you dont' have any locally data there will be an error message.

Screenshots (strongly suggested)

No visual changes

Does this MR meet the acceptance criteria?

Conformity

• I have included a changelog entry, or it's not needed. (Does this MR need a changelog?)
• I have added/updated documentation, or it's not needed. (Is documentation required?)
• I have properly separated EE content from FOSS, or this MR is FOSS only. (Where should EE code go?)
• I have added information for database reviewers in the MR description, or it's not needed. (Does this MR have database related changes?)
• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
• I have tested this MR in all supported browsers, or it's not needed.
• I have informed the Infrastructure department of a default or new setting change per definition of done, or it's not needed.

Security

Does this MR contain changes to processing or storing of credentials or tokens, authorization and authentication methods or other items described in the security review guidelines? If not, then delete this Security section.

• 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 to #326705 (closed)