cleanup: move json configuration functions in their own files

Improving maintainability by increasing 'separation of concern'.

Change-Id: I80355abf741c037f8834527e3304c80b83c8166e
Signed-off-by: Christopher Meis <christopher.meis@9elements.com>
diff --git a/src/meson.build b/src/meson.build
index f4b96a8..e4c2759 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -5,6 +5,7 @@
 executable(
     'entity-manager',
     'entity_manager.cpp',
+    'configuration.cpp',
     'expression.cpp',
     'perform_scan.cpp',
     'perform_probe.cpp',