AudioPlayerAgent에서 Offset, Milliseconds로 제공하는 Property추가 (#1154)

## Summary
- AudioPlayerAgent에서 Offset, Milliseconds로 제공하는 Property추가
- milliseconds로 제공하고 필요시에 사용처에서 seconds로 변환해서 사용할 수 있는 선택권 부여

NuguAgents/Sources/CapabilityAgents/AudioPlayer/AudioPlayerAgent.swift

@@ -49,6 +49,12 @@ public final class AudioPlayerAgent: AudioPlayerAgentProtocol {
         }
     }
 
+    public var offsetInMilliSeconds: Int? {
+        audioPlayerDispatchQueue.sync {
+            latestPlayer?.offset.truncatedMilliSeconds
+        }
+    }
+
     public var volume: Float = 1.0 {
         didSet {
             audioPlayerDispatchQueue.sync {

NuguAgents/Sources/CapabilityAgents/AudioPlayer/AudioPlayerAgentProtocol.swift

@@ -40,6 +40,11 @@ public protocol AudioPlayerAgentProtocol: CapabilityAgentable, TypedNotifyable {
     /// This function retrieves the duration(seconds) of the current `MediaPlayable` handled by the `AudioPlayerAgent`.
     var duration: Int? { get }
 
+    /// Returns the current time of the current player item.
+    ///
+    /// This function retrieves the offset(milliseconds) of the current `MediaPlayable` handled by the `AudioPlayerAgent`.
+    var offsetInMilliSeconds: Int? { get }
+
     /// The audio playback volume for the player.
     ///
     /// This function retrieves the volume of the current `MediaPlayable` handled by the `AudioPlayerAgent`.