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/Items/Bulletin Boards/BulletinBoardPackets.cs

@@ -233,7 +233,7 @@ namespace Server.Network
 
             Span<byte> textBuffer = stackalloc byte[TextEncoding.UTF8.GetMaxByteCount(longestTextLine)];
 
-            var writer = maxLength > 81920 ? new SpanWriter(maxLength) : new SpanWriter(stackalloc byte[maxLength]);
+            var writer = maxLength > 1024 ? new SpanWriter(maxLength) : new SpanWriter(stackalloc byte[maxLength]);
             writer.Write((byte)0x71); // Packet ID
             writer.Seek(2, SeekOrigin.Current);
             writer.Write((byte)(content ? 0x02 : 0x01)); // Command