Mssql integrated security (#30369)

* update go-mssqldb package

* mssql: support for Windows integrated security

Adds a dropdown to the config page to choose between
SQL Server auth and Windows auth. If the login/username
is empty then the go-mssqldb driver will use single sign on
(Windows integrated security) if on Windows.

* mssql: update ds - don't ignore the user column

pkg/services/sqlstore/datasource.go

@@ -243,6 +243,7 @@ func UpdateDataSource(cmd *models.UpdateDataSourceCommand) error {
 		// plain text fields to SecureJsonData.
 		sess.MustCols("password")
 		sess.MustCols("basic_auth_password")
+		sess.MustCols("user")
 
 		var updateSession *xorm.Session
 		if cmd.Version != 0 {