CT: Exception when opening item with linked asset in m6 app that worked in m5 app.

In M6.2, in an app based on a content type (using !content-type). An Exception occurs when trying to edit a content item, that was previously editable in m5. The content is still editable when using the !content-type-m5 directive. 

Since the app is always based on the same content-type definition, it should work correctly with the same content.

Seems to be related to linked assets 'JcrPathToIdentifierConverter'.

To reproduce bug:

• Add the attached content type definition to your resources.
• Add the attached app definition to your resources.
• Log out and in again.
• Open the app
• Add an item and link to an asset.
• Change the app definiton to use '!content-type' instead of '!content-type-m5'
• Close and reopen the app.
• Double click on the item that you created.
• Get an exception.

2020-05-07 16:22:58,264 ERROR agnolia.ui.framework.app.AppInstanceControllerImpl: Sub-app [detail] of app [tours] failed to startinfo.magnolia.jcr.RuntimeRepositoryException: javax.jcr.RepositoryException: invalid identifier: jcr:1044b3b8-30b1-48fe-8078-832b6cef8fb5at info.magnolia.ui.editor.converter.JcrPathToIdentifierConverter.convertToPresentation(JcrPathToIdentifierConverter.java:84) ~[magnolia-ui-framework-jcr-6.2.jar:?]at info.magnolia.ui.editor.converter.JcrPathToIdentifierConverter.convertToPresentation(JcrPathToIdentifierConverter.java:54) ~[magnolia-ui-framework-jcr-6.2.jar:?]

Dev notes:

• Test against 6.2.1
• Switch from read-only asset browser (dam-chooser) to 'assets app'
• Attempt to get rid of the dam-chooser workaround in favor of pre-configured asset-linkfield