feat: add bitwise NOT operator (~) with token, parser, and native implementation

Add TOKEN_TILDE token type and lexer support for the '~' character in the compiler. Implement the bitwise NOT operation as a native method on the Num class, operating on 32-bit unsigned integers. Include a new OPERATOR macro for prefix/infix operator grammar rules and add comprehensive test cases covering positive, negative, floating-point, and boundary values.

test/assignment/associativity.wren

@@ -0,0 +1,9 @@
+var a = "a"
+var b = "b"
+var c = "c"
+
+// Assignment is right-associative.
+a = b = c
+io.write(a) // expect: c
+io.write(b) // expect: c
+io.write(c) // expect: c

test/number/bitwise_not.wren

@@ -0,0 +1,23 @@
+io.write(~0) // expect: 4294967295
+io.write(~1) // expect: 4294967294
+io.write(~23) // expect: 4294967272
+
+// Max u32 value.
+io.write(~4294967295) // expect: 0
+
+// Past max u32 value.
+// TODO(bob): Is this right?
+io.write(~4294967296) // expect: 4294967295
+
+// Negative numbers.
+io.write(~-1) // expect: 0
+io.write(~-123) // expect: 122
+io.write(~-4294967294) // expect: 4294967293
+io.write(~-4294967295) // expect: 4294967294
+io.write(~-4294967296) // expect: 4294967295
+
+// Floating point values.
+io.write(~1.23) // expect: 4294967294
+io.write(~0.00123) // expect: 4294967295
+io.write(~345.67) // expect: 4294966950
+io.write(~-12.34) // expect: 11