'wikibase-item' datatype valueview works for 'wikibase-entityid' datavalues now

Instead of having this valueview widget specific to the 'wikibase-item' datatype, it will now work
for all 'wikibase-entityid' data values and can therefore be used for all valueview's supposed to
serve as input for 'wikibase-entityid' data value type based data types.

Change-Id: I6c7622e05f071b885618c9167d9dc9dd364a154c
Merge "'wikibase-item' datatype valueview works for 'wikibase-entityid' datavalues now"