add preferred language (#109)

* add explicit warning for zero/invalid duration media items

* set dateadded on plex media versions

* add media stream table

* save local media streams to db

* save plex media streams to db

* add preferred language settings (no validation)

* use preferred language if possible

* code cleanup

* proper language code validation

* force scan of all libraries to pull in media streams

ErsatzTV.Infrastructure/Migrations/20210328214310_Reset_LibraryLastScan_MediaStream.cs

@@ -0,0 +1,14 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+namespace ErsatzTV.Infrastructure.Migrations
+{
+    public partial class Reset_LibraryLastScan_MediaStream : Migration
+    {
+        protected override void Up(MigrationBuilder migrationBuilder) =>
+            migrationBuilder.Sql(@"UPDATE Library SET LastScan = '0001-01-01 00:00:00'");
+
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+        }
+    }
+}