Note: blocked by https://phabricator.wikimedia.org/T219378

User story:
As a normal user
In the metadata step in UW
I want to be able to add a statement block for a Property that doesn't already have statements
Where the statement Property accepts Q-items as a value (i.e. the property has data-type 'wikibase-entity')

We have this:
'depicts' statements only

We want this:

• an 'add statement' link
• clicking the link gives the user an auto-suggest
• the user types, and receives a list of properties with data-type 'wikibase-entity' (and that excludes properties we already have on the page)
• when the user selects a property a statement block similar to that for 'depicts' is created, and the user can add/edit values for the property like they do for depicts

Not in scope:

• qualifiers
• properties with data types that are not 'wikibase-entity'

Acceptance Criteria:

• in metadata step in UW user can add statement block for any property that has data type 'wikibase-entity'
• user can add/delete statements in new statement block
• user can remove all statements
• user can publish to save new statements