[VSA][FE] Update project-level metrics

As we aim for feature parity, we need to display the same metrics on project-level VSA as on group-level:

project level metrics	group level metrics

Proposal:

• Update the metrics components to use the GlSingleStat component for displaying metrics.
• Update the API requests to use the [new BE endpoints](#327570 (comment 605345917)

The following metrics will be available on the free version:

• New Issues
• Commits
• Deploys
• Deployment Frequency

In addition, the following metrics will be available for GitLab Premium only:

• Lead Time
• Cycle Time

/cc @ekigbo @npost