Add utf8 with bom (#2641)

* Change default file encoding

src/Sdk/DTExpressions2/Expressions2/ExpressionParser.cs

@@ -321,7 +321,7 @@ namespace GitHub.DistributedTask.Expressions2
                     context.Operators.Pop();
                 }
                 var functionOperands = PopOperands(context, parameterCount);
-                
+
                 // Node already exists on the operand stack
                 function = (Function)context.Operands.Peek();
 

src/Sdk/DTExpressions2/Expressions2/Sdk/Functions/FromJson.cs

@@ -21,4 +21,5 @@ namespace GitHub.DistributedTask.Expressions2.Sdk.Functions
                 return token.ToPipelineContextData();
             }
         }
-    }}
+    }
+}

src/Sdk/DTExpressions2/Expressions2/Sdk/Operators/Index.cs

@@ -213,7 +213,7 @@ namespace GitHub.DistributedTask.Expressions2.Sdk.Operators
             resultMemory = null;
             return null;
         }
-        
+
         private class FilteredArray : IReadOnlyArray
         {
             public FilteredArray()