Assess contrib Entity Reference management options

[eaton]

Core currently provides Entity References, but lacks an efficiently reusable browser to select from a large set of candidate entities; a way to create "child" entities in place when required by a "parent" entity, etc. The result is significant editorial overhead when creating "clusters" of interrelated nodes on any site with a highly relational content model.

Contrib approaches to this problem include:

• Entity Browser
• Inline Entity Form

We should assess these modules (and any others in the same domain) on the following criteria:

• Is the code in a state that's acceptable for core inclusion?
• Is the architectural approach flexible enough to handle a range of use cases and workflows?
• Are there existing sections of Core that could be simplified by using it?
• Is the editorial UX for entity selection/creation acceptable, or would it require additional work for inclusion?

[justafish]

Would this be possible to implement in the JS admin UI without needing to make any modifications to core? (I think the answer here is yes, but would love some input from someone with better knowledge @dawehner @alexpott )