Delay returning to suspend if woken up by rtc alarm

Currently mce does not know if rtc wakeup occurred due to clock
alarm. To avoid missing alarms altogether, returning to suspend
is now blocked at least for 5 seconds every time the device has
been resumed due to rtc alarm.

[mce] Delay returning to suspend if woken up by rtc alarm. Fixes JB#21702
Tune rtc-alarm and cpu-keepalive event logging

There have been some hard to reproduce alarm failure reports.

Logging important rtc-alarm and cpu-keepalive events also in release
sw should improve the chances of finding causes for any alarm failures
in the future.

Also some not so important events are demoted to DEBUG level.
Add enablers for ui side dimming

When normal display backlight brightness is close to minimum allowed by
kernel/hw, it is not possible to make any visible difference between on
and dimmed state by further backlight brightness tuning.

Now mce sends a D-Bus signal that lipstick can use to make the graphics
rendered on screen darker when this happens.

[mce] Add enablers for ui side dimming. Fixes JB#21683
Make MCE introspectable over D-Bus

Previously mce did not support org.freedesktop.DBus.Introspectable
D-Bus interface which required use of workarounds for making method
calls or listening to signals from qt and qml applications.

Augment mce dbus handler structures to hold XML introspection data too.

Allow registering of dummy signal handlers for the purposes of holding
introspection data for outbound signals.

Unify all dbus handler registration to happen via array-of-handers
functionality and provide introspection data for all method calls
supported by mce and (non-configurable) signals sent by mce.

Do diagnostic logging if mce still sends non-introspectable signals.

Implement org.freedesktop.DBus.Introspectable D-Bus interface for mce.

Allow use of org.freedesktop.DBus.Peer D-Bus interface with mce.

[mce] Make MCE introspectable over D-Bus. Fixes JB#21034
Do not use numeric exit value
Merge pull request #207 from spiiroin/add_introspect_support

Make MCE introspectable over D-Bus
Merge pull request #201 from spiiroin/end_of_cpu_keepalive

Delay returning to suspend if woken up by rtc alarm
Do not use literal value for ui side dimming percentage
Merge pull request #202 from spiiroin/ui_needs_to_dim

Add enablers for ui side dimming