Remove agl-service-voice-high dependency on Alexa voiceagent

Currently, the agl-service-voice-high has hard dependencies on the Alexa voiceagent API provided by alexa-voiceagent-service, which is problematic since it:

• bakes in a hard-coded vendor dependency that is not easily changed
• does not allow installing agl-service-voice-high by default and detecting voice support at runtime in applications

This issue will be used to track modifications to remove the dependencies and make voiceagents runtime configurable.