fix(core): Adds Hashed & Hierarchical Timer Wheel (#655)

- Removes TimerPriority
- Removes TimerThread
- Adds a [Hashed & Hierarchical Timer Wheel](http://www.cs.columbia.edu/~nahum/w6998/papers/ton97-timing-wheels.pdf)

Projects/Server.Tests/Tests/Network/Packets/Outgoing/MobilePacketTests.cs

@@ -4,6 +4,7 @@ using Xunit;
 
 namespace Server.Tests.Network
 {
+    [Collection("Sequential Tests")]
     public class MobilePacketTests : IClassFixture<ServerFixture>
     {
         [Fact]
@@ -328,11 +329,7 @@ namespace Server.Tests.Network
             var result = ns.SendPipe.Reader.TryRead();
             AssertThat.Equal(result.Buffer[0].AsSpan(0), expected);
         }
-    }
 
-    [Collection("Sequential Tests")]
-    public class SequentialMobilePacketTests : IClassFixture<ServerFixture>
-    {
         [Fact]
         public void TestMobileHits()
         {

Projects/Server.Tests/Tests/Network/Packets/Outgoing/PlayerPacketTests.cs

@@ -5,6 +5,7 @@ using Xunit;
 
 namespace Server.Tests.Network
 {
+    [Collection("Sequential Tests")]
     public class PlayerPacketTests : IClassFixture<ServerFixture>
     {
         [Theory]

Projects/Server.Tests/Tests/Network/Packets/Outgoing/VendorBuyPacketTests.cs

@@ -6,6 +6,7 @@ using Xunit;
 
 namespace Server.Tests.Network
 {
+    [Collection("Sequential Tests")]
     public class VendorBuyPacketTests : IClassFixture<ServerFixture>
     {
         [Theory]

Projects/Server.Tests/Tests/Network/Packets/Outgoing/VendorSellPacketTests.cs

@@ -5,6 +5,7 @@ using Xunit;
 
 namespace Server.Tests.Network
 {
+    [Collection("Sequential Tests")]
     public class VendorSellPacketTests : IClassFixture<ServerFixture>
     {
         [Fact]