[SYNC] synchronize with core

- reorder imports, foreign imports first
- use site properties instead oth site methods
- new form of exception handling
- update copyright string

Change-Id: I87d940ac43191ef5efb291b7d39498b406829062
(bug 59008) Add Arabic (ar) welcome template of Wiktionary and Wikiversity

patch submitted by Meno25

Additional fixes:
- remove old debug code
- import pywikibot directly

Change-Id: I23b0af4f00e48ab205633bc36d27f0dc00af17f1