Feat: Add RSwag to generate API Documentation

[atinybeardedman]

Overview

Adds the rswag gem and generates the default specs for the existing controllers. This generates interactive documentation to view the Open API Documentation for the endpoints.

Notes

• All the specs generated have been marked as pending, as they need to be filled in with correct details. These specs will actually hit the controller in order to generate the example data and will fail if they do not receive the correct response. Ideally future contributors to the repo can work incrementally on each spec to generate this example data.