Add CI pipeline documentation and enhance syncback architecture

- Introduced a new CI pipeline documentation file outlining steps for auto-fixing formatting, running linters, building, and testing.
- Documented the Rojo syncback architecture, detailing improvements to prevent duplicate file creation and format mismatches.
- Updated syncback logic to ensure existing instances are updated instead of creating duplicates, enhancing project file management.
- Added tests for encoding instances and handling nested children to improve reliability in syncback operations.

rojo-test/serve-tests/api_write_existing/default.project.json5

@@ -0,0 +1,10 @@
+{
+  "name": "api_write_existing",
+  "tree": {
+    "$className": "DataModel",
+    "ServerScriptService": {
+      "$className": "ServerScriptService",
+      "$path": "src"
+    }
+  }
+}