[FEATURE] Passing mapUnknownProperties down to SubConfiguration

This allows to effectively disable the checking for any child property.
Additionally the new configuration object will use late static binding
to make proper extension of the PropertyMappingConfiguration easier.

Credit goes to Marc Neuhaus who submitted the patch 7 months ago.

Change-Id: I81aa1a15b3cc82074d51b876dbb93764a3a6a261
Releases: master
Resolves: #37292