Add base URL to variant playlists (#2755)

* Add PathBase to variant playlists

* add commented code to help with testing

* update changelog

---------

Co-authored-by: Jason Dove <1695733+jasongdove@users.noreply.github.com>

ErsatzTV/Controllers/IptvController.cs

@@ -292,7 +292,7 @@ public class IptvController : StreamingControllerBase
     private async Task<string> GetMultiVariantPlaylist(string channelNumber)
     {
         var variantPlaylist =
-            $"{Request.Scheme}://{Request.Host}/iptv/session/{channelNumber}/hls.m3u8{AccessTokenQuery()}";
+            $"{Request.Scheme}://{Request.Host}{Request.PathBase}/iptv/session/{channelNumber}/hls.m3u8{AccessTokenQuery()}";
 
         Option<ChannelStreamingSpecsViewModel> maybeStreamingSpecs =
             await _mediator.Send(new GetChannelStreamingSpecs(channelNumber));