Move _handle_aliases() out of basic.py (#48578)

Refinements:
- return legal_inputs and update class properties
- remove redundant arguments from method and handle in caller
- add better exception types to method

* Add unit tests for handle_aliases

test/units/module_utils/basic/test_atomic_move.py

@@ -62,6 +62,7 @@ def fake_stat(mocker):
     stat1.st_mode = 0o0644
     stat1.st_uid = 0
     stat1.st_gid = 0
+    stat1.st_flags = 0
     yield stat1