add area get support and test (#381)

Consul.Test/OperatorTest.cs

@@ -142,5 +142,21 @@ public async Task Operator_AreaUpdate()
             Assert.Equal(area.RetryJoin, updatedArea.RetryJoin);
             Assert.Equal(area.PeerDatacenter, updatedArea.PeerDatacenter);
         }
+        [EnterpriseOnlyFact]
+        public async Task Operator_AreaGet()
+        {
+            var peerDataCenter = KVTest.GenerateTestKeyName();
+            var area = new AreaRequest { PeerDatacenter = peerDataCenter, UseTLS = true, RetryJoin = new string[] { "10.1.2.7", "10.1.2.0" } };
+            var createResult = await _client.Operator.AreaCreate(area);
+            var areaId = createResult.Response;
+
+            var req = await _client.Operator.AreaGet(areaId);
+            var result = req.Response.Single(x => x.ID == areaId);
+
+            Assert.Equal(areaId, result.ID);
+            Assert.Equal(area.UseTLS, result.UseTLS);
+            Assert.Equal(area.RetryJoin, result.RetryJoin);
+            Assert.Equal(area.PeerDatacenter, result.PeerDatacenter);
+        }
     }
 }

Consul/Interfaces/IOperatorEndpoint.cs

@@ -51,5 +51,7 @@ public interface IOperatorEndpoint
         Task<QueryResult<List<Area>>> AreaList(QueryOptions q, CancellationToken cancellationToken = default);
         Task<WriteResult<string>> AreaUpdate(AreaRequest area, string areaId, CancellationToken cancellationToken = default);
         Task<WriteResult<string>> AreaUpdate(AreaRequest area, string areaId, WriteOptions q, CancellationToken cancellationToken = default);
+        Task<QueryResult<Area[]>> AreaGet(string areaId, CancellationToken cancellationToken = default);
+        Task<QueryResult<Area[]>> AreaGet(string areaId, QueryOptions q, CancellationToken cancellationToken = default);
     }
 }

Consul/Operator.cs

@@ -327,6 +327,20 @@ public async Task<WriteResult<string>> AreaUpdate(AreaRequest area, string areaI
             var req = await _client.Put<AreaRequest, Area>($"/v1/operator/area/{areaId}", area, q).Execute(ct).ConfigureAwait(false);
             return new WriteResult<string>(req, req.Response.ID);
         }
+        /// <summary>
+        /// AreaGet returns a single network area
+        /// </summary>
+        public Task<QueryResult<Area[]>> AreaGet(string areaId, CancellationToken ct = default)
+        {
+            return AreaGet(areaId, QueryOptions.Default, ct);
+        }
+        /// <summary>
+        /// AreaGet returns a single network area
+        /// </summary>
+        public Task<QueryResult<Area[]>> AreaGet(string areaId, QueryOptions q, CancellationToken ct = default)
+        {
+            return _client.Get<Area[]>($"/v1/operator/area/{areaId}", q).Execute(ct);
+        }
     }
 
     public class ConsulLicense