entity-manager: writeJsonFiles: fix throw on mkdir

writeJsonFiles is fixed to not throw in case the directory cannot be
created and instead use the overload with std::error_code to relay the
error to the caller instead.

Discovered the issue in unit testing:

```
C++ exception with description "filesystem error: cannot create directory: Permission denied [/var/configuration/]" thrown in the test body.
```

Tested: Inspection only.

Change-Id: I4c1c09cad5a560e9db9f994579ff9af2b5280c00
Signed-off-by: Alexander Hansen <alexander.hansen@9elements.com>
diff --git a/src/entity_manager/configuration.cpp b/src/entity_manager/configuration.cpp
index 7532fc1..1e4ceac 100644
--- a/src/entity_manager/configuration.cpp
+++ b/src/entity_manager/configuration.cpp
@@ -186,7 +186,12 @@
         return true;
     }
 
-    std::filesystem::create_directory(configurationOutDir);
+    std::error_code ec;
+    std::filesystem::create_directory(configurationOutDir, ec);
+    if (ec)
+    {
+        return false;
+    }
     std::ofstream output(currentConfiguration);
     if (!output.good())
     {