add periodic file scanner, parallelize downloads, fix transient files being readded when not necessary, fix disposal of players on plugin shutdown

MareSynchronos/FileCacheDB/FileCacheEntity.cs

@@ -0,0 +1,13 @@
+#nullable disable
+
+
+namespace MareSynchronos.FileCacheDB
+{
+    public partial class FileCacheEntity
+    {
+        public string Hash { get; set; }
+        public string Filepath { get; set; }
+        public string LastModifiedDate { get; set; }
+        public int Version { get; set; }
+    }
+}