MDEV-22176 Add JUnit support to MTR to generate XML test result

A new parameter has been added called xml-report, with which the
filename of the XML file is given to which the XML result is
written. There is also xml-package for adding a package value in
the XML output. Example usage:
./mysql-test-run.pl main.events_bugs innodb.count_distinct
main.explain_json innodb.file_format_defaults json.json_no_table
--suite=main,innodb,json --force --xml-report=build123456789.xml
--xml-package=simpletestrun

mysql-test/lib/My/Tee.pm

@@ -10,7 +10,7 @@ sub PUSHED
   open($copyfh, '>', "$::opt_vardir/log/stdout.log")
     or die "open(>$::opt_vardir/log/stdout.log): $!"
       unless $copyfh;
- bless { }, shift;
+  bless { }, shift;
 }
 
 sub WRITE