cleanup: move EM service code in EM directory

Improving repository structure increases maintainability.

Change-Id: I7f746a5d491dda256a06143f516e7d078a761c14
Signed-off-by: Christopher Meis <christopher.meis@9elements.com>
diff --git a/src/meson.build b/src/meson.build
index 3699484..b8a7f0e 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -2,28 +2,7 @@
 cpp_args += ['-DSYSCONF_DIR="' + sysconfdir + '/"']
 installdir = join_paths(get_option('libexecdir'), 'entity-manager')
 
-executable(
-    'entity-manager',
-    'entity_manager.cpp',
-    'configuration.cpp',
-    'expression.cpp',
-    'dbus_interface.cpp',
-    'perform_scan.cpp',
-    'perform_probe.cpp',
-    'overlay.cpp',
-    'topology.cpp',
-    'utils.cpp',
-    cpp_args: cpp_args + ['-DBOOST_ASIO_DISABLE_THREADS'],
-    dependencies: [
-        boost,
-        nlohmann_json_dep,
-        phosphor_logging_dep,
-        sdbusplus,
-        valijson,
-    ],
-    install: true,
-    install_dir: installdir,
-)
+subdir('entity_manager')
 
 if get_option('fru-device')
     cpp_args_fd = cpp_args