Refactor: remove direct volume control from Skill

[krisgesling]

Currently the Alarm Skill directly manipulates the volume via ALSA. This should be done by emitting the relevant messages on the Mycroft Message bus so that each platform can handle the volume in its own specific way. At the very least this should be handled by the Volume Skill, not the Alarm Skill.

The volume control messages can be found at:
https://mycroft-ai.gitbook.io/docs/mycroft-technologies/mycroft-core/message-types#volume-control

[Mabenan]

In my opinion the volume shouldn't be changed at all by an alarm skill.
Or at least it should be an option.

The rest of it is true. Especially as the handling of the Mixer is different in this skill as it is in the Volume Skill. which also lacks some soundhardware on a pi but this is again another story.