maas dns role for configuring maas dns domains and records

maas dns role for configuring maas dns domains and records

- Configures DNS entries for hosts (e.g., main interfaces, IPMI interfaces) using `dns_domains` and inventory variables (`ip`, `ipmi`).
- Dynamically sets `maas_cluster_instance.host` via `maas_api_url` in `defaults/main.yml`, with credentials (`customer_key`, `token_key`, `token_secret`) loaded from a secrets file (`secrets/maas.yml`).
- Filters inventory to process only hosts with `ip` or `ipmi` variables, excluding groups like `all` and `ungrouped`.
- Cleans up unwanted DNS records and domains not in `dns_domains` or `excluded_domains`, skipping default MAAS domains.
- Skips NS record creation due to module limitations, with instructions for manual creation via MAAS CLI/UI.
- Includes comprehensive `README.md` with:
  - Inventory example with `mac`, `ip`, `ipmi`, and `bmc` attributes (e.g., `server01.example.com mac=00:1a:2b:3c:4d:5e ip=192.168.1.11 ipmi=192.168.2.11 bmc=00:1a:2b:3c:4d:5f`).
  - Setup instructions for inventory, secrets, and variables.
  - Troubleshooting for common issues (e.g., network errors, missing `dns_domains`).
  - Performance tips (e.g., fact caching).
- Ensures idempotency and supports large inventories.