Update project configuration and snapshot files

- Changed the default project file from `plugin.project.json` to `plugin.project.json5` in `build.rs`.
- Added new project configuration files in JSON5 format for various test cases, including `default.project.json5`, `client_in_folder`, `csv_bug_145`, and others.
- Updated snapshot files to reflect changes in instance structure and properties, ensuring consistency with the new project configurations.
- Removed unnecessary script and module instances from snapshot files to streamline the testing process.

rojo-test/syncback-tests/project_reserialize/expected/default.project.json5

@@ -10,7 +10,7 @@
         "$path": "attribute_mismatch.luau"
       },
       "property_mismatch": {
-        "$path": "property_mismatch.project.json"
+        "$path": "property_mismatch.project.json5"
       },
       "$properties": {
         "EditorLiveScripting": {