Add project configuration and test files in JSON5 format

- Introduced new configuration files for testing, including `default.project.json5`, `client_in_folder`, and others.
- Updated existing project files to use JSON5 format, ensuring consistency across configurations.
- Added new Lua scripts and model files to support various test cases.
- Adjusted snapshot files to align with the new project structure and properties.

test-projects/nested_partitions/default.project.json5

@@ -0,0 +1,9 @@
+{
+  "name": "nested-partitions",
+  "tree": {
+    "$path": "outer",
+    "inner": {
+      "$path": "inner"
+    }
+  }
+}