Created ECN# autocomplete for PCR3 docs

MesaFabApproval.API/Controllers/ECNController.cs

@@ -53,4 +53,36 @@ public class ECNController : ControllerBase {
             }
         }
     }
+
+    [HttpGet]
+    [Route("ecn/allNumbers")]
+    public async Task<IActionResult> GetAllECNNumbers() {
+        DateTime start = DateTime.Now;
+        bool isInternalError = false;
+        string errorMessage = "";
+
+        try {
+            _logger.LogInformation($"Attempting to get all ECN#s");
+            
+            IEnumerable<int> allEcnNumbers = await _ecnService.GetAllECNNumbers();
+
+            return Ok(allEcnNumbers);
+        } catch (Exception ex) {
+            isInternalError = true;
+            errorMessage = $"Cannot get all ECN#s, because {ex.Message}";
+            return Problem(errorMessage);
+        } finally {
+            string metricName = "GetAllECNNumbers";
+            DateTime end = DateTime.Now;
+            double millisecondsDiff = (end - start).TotalMilliseconds;
+            _monInClient.PostAverage(metricName + "Latency", millisecondsDiff);
+
+            if (isInternalError) {
+                _logger.LogError(errorMessage);
+                _monInClient.PostStatus(metricName, StatusValue.Critical);
+            } else {
+                _monInClient.PostStatus(metricName, StatusValue.Ok);
+            }
+        }
+    }
 }