ncm-filecopy: Provide ability to remove immutable bit

[jrha]

We recently found some systems where a user had set the immutable bit chattr +i … on a file to prevent their changes to it being overwritten by Quattor. This rather predictably caused filecopy to error:

2021/10/28-15:34:36 [INFO] Checking file /usr/sbin/foo...
2021/10/28-15:34:36 [INFO] Checking file /var/lock/foo...
2021/10/28-15:34:36 [ERROR] uncaught error exception in component: filecopy
2021/10/28-15:34:36 [ERROR] *** unlink(/root/foo/bar): Operation not permitted
2021/10/28-15:34:36 [INFO] Configure on component filecopy executed, 1 errors, 0 warnings
2021/10/28-15:34:36 [VERB] No events to report

We should enable filecopy (and probably other components) to remove the immutable bit when touching files.