feat: add test verifying carriage returns are treated as whitespace in parser

Add a new test file `test/ignore_carriage_returns.wren` that sprinkles carriage
return characters (`\r`) in various positions within source code to confirm the
parser correctly ignores them as whitespace. The test includes a deliberate
compile error to validate that line numbering remains accurate despite the
presence of carriage returns.

test/ignore_carriage_returns.wren

@@ -0,0 +1,6 @@
+// Sprinkle some carriage returns to ensure they are ignored anywhere:
+IO␍.print("one"␍)
+IO.print␍("two")
+
+// Generate a compile error so we can test that the line number is correct.
++ * // expect error