[Enhancement] [RHEL/6] Add audit syscall remediations for '*chown*, *chmod* & *xattr' groups

This proposal creates remediation scripts for RHEL-6 audit system calls checks belonging to:
* chmod
* chown, or
* *xattr

groups. The point behind each of the remediation script is as follows:
* depending on the architecture add either just 32bit or both 32bit & 64bit rule version,
* search existing /etc/audit/audit.rules structure for common rule pattern for that audit key

For each of the rules found compare it with the expected output rule form:
* if existing rule is completely covered (would be completely absorbed) with the common rule for these syscalls to be added, delete it (not to have two different rules containing the same syscall for the same architecture & key in audit.rules),
* if existing rule wouldn't be completely covered / absorbed (IOW it contains also syscalls from other groups), remove just syscalls for the group we are performing remediation script for (example: would we try to remediate -S fchmod rule & existing rule would have the form:
  ```-S fchmod -S lchown```
the ```-S fchmod``` part would be deleted, and just ```-S lchown``` syscall part kept in original rule form. At the end common rule having ```-S chmod -S fchmod -S fchmodat``` would be added to /etc/audit/audit.rules file yet).
  Then if this updated rule (for the same arch & audit key) isn't present in /etc/audit/audit.rules yet, insert it.
* at the end insert the common rule for particular group of syscalls (as specified in /usr/share/doc/audit-NVR/stig.rules audit file combining rules from same group into one rule for efficiency) if it's not present in /etc/audit/audit.rules file yet (to prevent duplicates).

Testing report:
--
The change has been tested on RHEL-6 for each of the 13 audit system calls, the remediation scripts are being added for & for various combinations of existing /etc/audit/audit.rules file content & seems to be working properly (from what I have tested & can tell). Also, it should be working at both 32bit / 64bit system versions properly (from what I have tested).

Please review.

Thanks, Jan.