feat: add bitwise left shift, right shift, and xor operand tests

Add comprehensive test files for bitwise lsh, rsh, and xor operations
covering basic cases, max u32 boundary, past max u32 wrap, and operand
type error checks for non-numeric right operands.

test/number/bitwise_xor.wren

@@ -0,0 +1,15 @@
+IO.print(0 ^ 0) // expect: 0
+IO.print(1 ^ 1) // expect: 0
+IO.print(0 ^ 1) // expect: 1
+IO.print(1 ^ 0) // expect: 1
+IO.print(2863311530 ^ 1431655765) // expect: 4294967295
+IO.print(4042322160 ^ 1010580540) // expect: 3435973836
+
+// Max u32 value.
+IO.print(4294967295 ^ 4294967295) // expect: 0
+
+// Past max u32 value.
+IO.print(4294967296 ^ 4294967296) // expect: 0
+
+// TODO: Negative numbers.
+// TODO: Floating-point numbers.