add missing file selectionPos

forgot to add it in one of the previous commits

src/ui/bigtext/selectionPos.py

@@ -0,0 +1,11 @@
+class SelectionPos:
+    def __init__(self, index: int, is_in_left_half: bool, num_bytes_of_char: int):
+        self.index = index
+        self.is_in_left_half = is_in_left_half
+        self.num_bytes_of_char = num_bytes_of_char
+
+    def __repr__(self):
+        return f"{self.index}{'🞀' if self.is_in_left_half else '🞂'}({self.num_bytes_of_char})"
+
+    def pos(self):
+        return self.index + (0 if self.is_in_left_half else self.num_bytes_of_char)