Fixed AudFormat and WavFormat implementations of ISoundFormat.LengthInSeconds

- Fixed a rounding issue in `WavReader.WaveLength()`.
- Fixed `AudReader.SoundLength()` not resetting the stream position.
- Fixed crashes caused by disposed streams because `LengthInSeconds` would try and calculate the length on the fly. It is now precalculated and cached (making it consistent across all 5 current `ISoundFormat` implementations).
- Fixed a crash in `AudReader.LoadSound()`'s `out Func<Stream> result` because that func would try and access the disposed stream's `Length` property. That works for `SegmentStream`, but not for `FileStream`.
- Fixed frameCount/soundLength label positioning in the AssetBrowser window to avoid text clipping .

mods/cnc/chrome/assetbrowser.yaml

@@ -190,7 +190,7 @@ Container@ASSETBROWSER_PANEL:
 							MinimumValue: 0
 						Label@FRAME_COUNT:
 							X: PARENT_RIGHT - WIDTH + 5
-							Y: 1
+							Y: 0
 							Width: 80
 							Height: 25
 							Font: TinyBold

mods/common/chrome/assetbrowser.yaml

@@ -180,7 +180,7 @@ Background@ASSETBROWSER_PANEL:
 					MinimumValue: 0
 				Label@FRAME_COUNT:
 					X: PARENT_RIGHT - WIDTH + 5
-					Y: 1
+					Y: 0
 					Width: 85
 					Height: 25
 					Font: TinyBold