Implement Claim.__eq__
Implement Claim.__eq__

Claims are same when they are derived from the same
property, have the same target and qualifiers
(which are also claims, so this comparison happens
recursively).

Bug: T76615
Change-Id: Ib082ebf8c5a11f1e79e3d863d4f8d4b1fe2ef8da

wikimedia/pywikibot-core,wikimedia/pywikibot-core,PersianWikipedia/pywikibot-core