Support xz compression format when registering templates

[kiranchavala]

ISSUE TYPE

• Improvement Request

COMPONENT NAME

Component: template, kvm

CLOUDSTACK VERSION

4.18 

SUMMARY

Support xz compression format when registering templates

Steps to reproduce the issue

1. Register a qcow2 template which is compressed by the xz format

https://cloud.centos.org/centos/7/images/CentOS-7-aarch64-GenericCloud-1606.qcow2.xz

2. The registration fails as currently cloudstack supports the following formats

COMMPRESSION_FORMATS = ImmutableSet.of("zip", "bz2", "gz");

Screenshot

Expected behavior

We should support the xz format compression, as it is also widely used compression format for linux images