More cleanup

- Moved all bot files to src/NadekoBot
- Fixed tests path in ci
- Fixed some warnings in MusicService
- Cleaned up csproj slightly

src/NadekoBot.Coordinator/Program.cs

@@ -1,34 +0,0 @@
-using NadekoBot.Core.Services;
-using System.Diagnostics;
-using System.Threading.Tasks;
-
-namespace NadekoBot
-{
-    public sealed class Program
-    {
-        public static async Task Main(string[] args)
-        {
-            var pid = Process.GetCurrentProcess().Id;
-            System.Console.WriteLine($"Pid: {pid}");
-            if (args.Length == 2
-                && int.TryParse(args[0], out int shardId)
-                && int.TryParse(args[1], out int parentProcessId))
-            {
-                await new NadekoBot(shardId, parentProcessId == 0 ? pid : parentProcessId)
-                    .RunAndBlockAsync();
-            }
-            else
-            {
-                await new ShardsCoordinator()
-                    .RunAsync()
-                    .ConfigureAwait(false);
-#if DEBUG
-                await new NadekoBot(0, pid)
-                    .RunAndBlockAsync();
-#else
-                await Task.Delay(-1);
-#endif
-            }
-        }
-    }
-}