Provide mechanism to validate API keys. Re-organise structure to reflect new responsibility

src/Robware.Api.Auth/Controllers/ApiController.cs

@@ -0,0 +1,21 @@
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.Logging;
+using Robware.Auth.API;
+
+namespace Robware.Api.Auth.Controllers {
+	[ApiController]
+	[Route("[controller]")]
+	public class ApiController : ControllerBase {
+		private readonly ILogger<ApiController> _logger;
+		private readonly IApiKeyValidator _apiKeyValidator;
+
+		public ApiController(ILogger<ApiController> logger, IApiKeyValidator apiKeyValidator) {
+			_logger = logger;
+			_apiKeyValidator = apiKeyValidator;
+		}
+
+		[HttpGet(nameof(Validate))]
+		public async Task<ActionResult> Validate(string key) => await _apiKeyValidator.Validate(key) ? (ActionResult) Ok() : Unauthorized();
+	}
+}