Reduce duplicated code in qubes.xml load
Reduce duplicated code in qubes.xml load

Parse common attrs in separate function.
Side effect: possibility to set custom TemplateVM label

woju/qubes-core-admin,QubesOS/qubes-core-admin,woju/qubes-core-admin,marmarek/qubes-core-admin,QubesOS/qubes-core-admin,marmarek/qubes-core-admin,QubesOS/qubes-core-admin,woju/qubes-core-admin,woju/qubes-core-admin,marmarek/qubes-core-admin