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/Multis/Houses/HousePackets.cs

@@ -106,6 +106,8 @@ namespace Server.Multis
             using var planesWriter = new SpanWriter(planeLength * planeCount);
 
             Span<bool> planesUsed = stackalloc bool[9];
+            planesUsed.Clear();
+
             int index;
             var totalPlaneOffsets = 0;
             var totalPlanes = 0;