feat: add GA4GH Service Info-related functions

[uniqueg]

Each of our backend microservices implements an OpenAPI specification with one or more operations related to viewing or setting a service instance's "service info". Each of these are built on the GA4GH Service Info API, which defines a minimal set of properties for describing services.

For all GA4GH OpenAPI specifications, a GET /service-info operation is already defined. However, operations for POSTing and PUTting service info details are not defined. Moreover, our services that are not implementing GA4GH OpenAPI specifications also define the GET /service-info again.

This leads to there being multiple (core) service info OpenAPI definitions available in our organization, as well as mutliple implementations for controllers to operationalize service info handling.

We therefore would like to:

• Provide definite OpenAPI definitions for GET, POST and PUT operations for the /service-info route that can be reused in each of our services (several will not need definitions for the GET operation, because they already inherit it from GA4GH specs, but some will; all of them will need POST and PUT operations)
• Provide definite controllers for all service info operations to be imported in each service