made builtins usable and added tests (#63)

* made all buitlins operational (except ecsda and output) and added individual tests for each one of them

* added number of output cells for builtins with multiple outputs

* updated test file

* fixed TO_SIGNED_INTEGER naming coherence

cairo0/builtins/bitwise_builtin.cairo

@@ -0,0 +1,15 @@
+%builtins bitwise
+
+from starkware.cairo.common.cairo_builtins import BitwiseBuiltin
+
+func main{bitwise_ptr: BitwiseBuiltin*}() {
+    assert bitwise_ptr.x = 12;  // Binary 1100
+    assert bitwise_ptr.y = 10;  // Binary 1010
+    assert bitwise_ptr.x_and_y = 8;  // Binary 1000
+    assert bitwise_ptr.x_xor_y = 6;  // Binary 0110
+    assert bitwise_ptr.x_or_y = 14;  // Binary 1110
+
+    let bitwise_ptr = bitwise_ptr + BitwiseBuiltin.SIZE;
+
+    return ();
+}