[audiorouting] Derive music playback from media_state. Fixes JB#36733
[audiorouting] Derive music playback from media_state. Fixes JB#36733

Relying on volume limit heuristics to determine whether some application
is doing audio playback is unreliable. And if MCE makes a wrong guess
it affects for example volume key input policy (volume keys can't be
used for adjusting playback volume).

When possible, use factual media state information instead of heuristics.

Signed-off-by: Simo Piiroinen <6d5e5360bed3d486f7d9fb26b0f737f7d4fd45ee@jollamobile.com>

spiiroin/mce,spiiroin/mce,spiiroin/mce,spiiroin/mce