LibVT+Terminal: Implement line wrapping

This commit implements line wrapping in the terminal, and tries its best
to move the cursor to the "correct" position.

Userland/Libraries/LibVT/Position.h

@@ -51,4 +51,15 @@ private:
     int m_column { -1 };
 };
 
+struct CursorPosition {
+    u16 row { 0 };
+    u16 column { 0 };
+
+    void clamp(u16 max_row, u16 max_column)
+    {
+        row = min(row, max_row);
+        column = min(column, max_column);
+    }
+};
+
 }