qubes/features: handle recursive templates
qubes/features: handle recursive templates

Have features.check_with_template() check the template recursively.
The longest path (currently) is: DispVM -> AppVM -> TemplateVM.

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