Scrobble check can miss tracks if the currently playing track is not scrobbled

[ndm13]

Currently the scrobble detection includes the currently playing track under the assumption that if it's not scrobbled already it will be. This isn't always true - apparently the Last.FM app will mark music from Google ambient music detection as now playing but will not scrobble it. There may be other situations where this happens also.

This will require reworking the now playing and history calls. If now playing is in history then we keep our current behavior, otherwise we ignore the currently playing track when reporting (don't scrobble it, record the previous track as last scrobbled, offset last run time by duration) and let the next pull scrobble it if it hasn't been scrobbled already.