tests/basics: Split out specific slice tests to separate files.

So they can be automatically skipped if slice is not enabled.

tests/basics/list_slice.py

@@ -1,6 +1,11 @@
 # test list slices, getting values
 
 x = list(range(10))
+
+print(x[1:])
+print(x[:-1])
+print(x[2:3])
+
 a = 2
 b = 4
 c = 3