Removed jQuery.wikibase.claimview

As the concept of Claim is to be removed (see https://github.com/wmde/WikibaseDataModel/pull/317),
this change removes the corresponding UI concept of claimview and decreases complexity resulting
from statementview having to encapsulate claimview while claimview should need to remain an
independent widget (as long as there is Claim in the data model). There is no reason to have the
concept of claimview, nor the term claim at all remain in the front-end. The change anticipates
the data model change by merging main snak and qualifiers related functionality from claimview
into statementview.

Requires adjusting the browser tests: https://github.com/wmde/WikidataBrowserTests/pull/35

Change-Id: I4060c1f9ff56970e69a59b85ca716848f3dcef53
Merge "Removed jQuery.wikibase.claimview"