Rename events:
- domain-feature-set -> domain-feature-set:feature
- domain-feature-delete -> domain-feature-delete:feature
- domain-tag-add -> domain-tag-add:tag
- domain-tag-delete -> domain-tag-delete:tag
Make it consistent with property-* events. It makes more sense to
include tag/feature name in event name, so handler can watch a single
tag/feature - which is the most common case. Otherwise, most handlers
would begin with `if feature == '...'` anyway, wasting time on most
events.
In cases where multiple features/tags should be handled by a single
handler, it is now possible to register a handler with wildcard, for
example `domain-feature-set:*`.
Use '<option name="option_name">option_value</option>' instead of
'<options option_name="option_value"/>'. It's more consistent with the
rest of qubes.xml - have one thing per element.
Also, add options deserialization test.
While at it, adjust implementation to specification: tags don't have
value, only one bit of information (present/not present).
FixesQubesOS/qubes-issues#2686
Implement required event handlers according to documentation in
qubes.devices.
A modification of qubes.devices.DeviceInfo is needed to allow dynamic,
read-only properties.
QubesOS/qubes-issues#2257
Allow device plugin to list attached and available devices. Enforce
at API level every device being exposed by some domain.
This commit only changes devices API, but not update existing users
(pci) yet.
QubesOS/qubes-issues#2257
