Acceptance criteria:

• functionality-wise there should be no regression compared to the current status of M5-based link field.
  • i.e. one should be able to reference the content items from arbitrary apps
• the definition should be prepared to allow referencing content from sources that aren't bound to any app (see the technical steps below)
• Preview of selected item (image, contact) is displayed next to the link field.

The following technical steps need to be accomplished:

• come up with a link field definiton that is less bound to the apps, so that we would eventually be able to link the content that is not connected to any app (content type, remote service etc). Ideally the definition should not require the app to be present, however though, it should still be possible to delegate the chooser resolution to an app.
• carefully design interaction with chooser dialog (should be done as a joint venture with chooser dialog story DEV-974, which is a pre-requisite for this story)
• provide Vaadin 8 based field factory

tips:

• some relation to the select fields may be traced (both connect to a datasource after all, both select smth)