fix: Fixes sending packets and sidesteps a major issue with stackalloc and PGO in .NET 8 (#1607)

### Summary
- Works around a sneaky edge case bug in the JIT with stackalloc where sometimes the buffer is not zero'd.
- Fixes SendDisplayBoatHS
- Fixes sending health bars in the `SendEverything()` logic.
- Fixes a bug in sizing for some string helper functions.

### Developer Note
We are enabled `SkipLocalsInit` - do not rely on `stackalloc` to be zero'd. To zero the buffer, use `span.Clear();`

Closes #1606

Projects/UOContent/Engines/Party/PartyPackets.cs

@@ -140,15 +140,14 @@ namespace Server.Engines.PartySystem
                 return;
             }
 
-            Span<byte> buffer = stackalloc byte[10];
-            var writer = new SpanWriter(buffer);
+            var writer = new SpanWriter(stackalloc byte[10]);
             writer.Write((byte)0xBF); // Packet ID
             writer.Write((ushort)10);
             writer.Write((ushort)0x06); // Sub-packet
             writer.Write((byte)0x07); // command
             writer.Write(leader);
 
-            ns.Send(buffer);
+            ns.Send(writer.Span);
         }
     }
 }