[virt-tools-list] [virt-manager gui feature request] check box for "locked" memory backing

[Joachim Wagner]

While various cli options for memory backing have been introduced in 2014, the 
virt-manager GUI doesn't offer any memory options other than current and 
maximum allocation under open -> view -> details -> memory. The "locked" 
memory backing option is probably the most easy to to understand and can have 
huge impact when the host also acts as a file server or runs write-intense 
applications. It would be useful to many users to have a check box for it in 
the GUI.

Indications for a need for this check box:
 * https://serverfault.com/questions/561446/how-can-i-keep-important-vms-in-memory-without-disabling-swap/
 * https://serverfault.com/questions/477886/why-does-host-swap-out-vms-when-there-are-16gb-of-buffer-cache-and-swappiness

The other options may also be useful but typical users will require much more 
guidance than offered in the libvirt documentation. I only start understanding  
them reading <https://www.suse.com/documentation/sles-15/singlehtml/
article_vt_best_practices/article_vt_best_practices.html>.