Add support for triggers that modify values in the inserted/updated r…

…ow to SQL Server

For inserts inner join the INSERTED table instead of reading values directly from it.
For updates use the relationat implementation that doesn't use INSERTED table.

Fixes #6474

src/Microsoft.EntityFrameworkCore.Relational/Update/UpdateSqlGenerator.cs

@@ -155,7 +155,8 @@ protected virtual ResultSetMapping AppendSelectAffectedCommand(
             AppendFromClause(commandStringBuilder, name, schema);
             // TODO: there is no notion of operator - currently all the where conditions check equality
             AppendWhereAffectedClause(commandStringBuilder, conditionOperations);
-            commandStringBuilder.Append(SqlGenerationHelper.StatementTerminator).AppendLine();
+            commandStringBuilder.Append(SqlGenerationHelper.StatementTerminator).AppendLine()
+                .AppendLine();
 
             return ResultSetMapping.LastInResultSet;
         }