Make all types support "!" so "if (!foo)" works reliably for all objects.

test/list/all_non_bool_returning_fn.wren

@@ -1 +1 @@
-[1, 2, 3].all {|x| "string" } // expect runtime error: String does not implement method '!' with 0 arguments.
+IO.print([1, 2, 3].all {|x| "truthy" }) // expect: true

test/list/not.wren

@@ -0,0 +1,2 @@
+IO.print(![1, 2]) // expect: false
+IO.print(![])     // expect: false

test/null/not.wren

@@ -0,0 +1 @@
+IO.print(!null) // expect: true

test/number/not.wren

@@ -0,0 +1,2 @@
+IO.print(!123) // expect: false
+IO.print(!0) // expect: false

test/object/not.wren

@@ -0,0 +1,2 @@
+class Foo {}
+IO.print(!(new Foo)) // expect: false

test/string/not.wren

@@ -0,0 +1,2 @@
+IO.print(!"s") // expect: false
+IO.print(!"") // expect: false