Added a new test class `EndpointsApiTests` to validate the `Endpoints` API functionality in the `ReC.Client`.
Tests include:
- Dependency injection resolution for the `Endpoints` API.
- Behavior of `CreateAsync` with minimal payload.
- Behavior of `UpdateAsync` with an unknown ID.
- Validation of `DeleteAsync` sending payload as query string.
Introduced necessary `using` directives and utilized the `CreateScopedClient` helper method for resource management.
