BUG-579: Added SchemaContextHolder interface to RuntimeGeneratedMappingServiceImpl to provide its schemaContext

Change-Id: Iceb5af637ba36ec23c8874a830b7d804ea7f345d
Signed-off-by: Martin Bobak <mbobak@cisco.com>
Signed-off-by: Tony Tkacik <ttkacik@cisco.com>
(cherry picked from commit 9312c7b32390f9e1f10312a49fa7138f9876a158)