Adding Health endpoint

[otherview]

Description

A health check service that lives inside the node as an API endpoint.

I think it's a good illustrative start for a PR, there are a few tech choices made that I consider would be worth discussing, such as:

• Should this endpoint live in the Admin API ?
• Should this be a singleton service ?
• Is the naming on point ?

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• [x] New feature (non-breaking change which adds functionality)

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] New and existing E2E tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules
• [x] I have not added any vulnerable dependencies to my code