Refactor MIG build process to run asynchronously with optional wait control

- Moved MIG data build commands into a dedicated 02_build_data.yml task file.
- Added async execution (async: 3600, poll: 0) for non-blocking build.
- Introduced mig_wait_for_build variable to optionally wait for completion.
- Added debug message to inform how to disable waiting via build_data.wait_for=false for performance.
- Updated config to use nested build_data.enabled and build_data.wait_for structure.
- Adjusted variable lookups accordingly.

https://chatgpt.com/share/689b54d2-e3b0-800f-91df-939ebc5e12ef

roles/web-app-mig/config/main.yml

@@ -36,4 +36,11 @@ server:
       - "mig.{{ primary_domain }}"
     aliases:
       - "meta-infinite-graph.{{ primary_domain }}"
-build_data: true  # Enables the building of the meta data which the graph requiers
+
+build_data: 
+  # This shouldn't be relevant anymore, because the data is anyhow build async in background
+  # Enables the building of the meta data which the graph requiers
+  enabled:  true
+
+  # Recommended to set this to false in inventory to optimize speed
+  wait_for: true