Incorrect rewrite for switch assignment (using new language features)

```
/* bool drawin = corner switch {
*/ //Auto-excluded to prevent exceptions - see docs PathCorner.UpperLeft => drawBorder[3],
PathCorner.UpperRight => drawBorder[0],
PathCorner.LowerRight => drawBorder[1],
PathCorner.LowerLeft => drawBorder[2],
=> true,

So it thorws an "; missing" error, due to its not excluding enough.

This is the original:

bool drawin = corner switch {
PathCorner.UpperLeft => drawBorder[3],
PathCorner.UpperRight => drawBorder[0],
PathCorner.LowerRight => drawBorder[1],
PathCorner.LowerLeft => drawBorder[2],
=> true,
};
```

Start with the switch-expression assignment shown in the issue and trace the C# rewrite handling for this syntax. Compare the transformed result with the original example; done when the rewrite preserves the complete switch expression without producing a missing-semicolon error.

Scritto dal modello di indicizzazione a partire dal testo della issue.