feat: add data collection endpoint and rule modules AB#9312

[kfaessen]

Adds two modules under modules/azure/: data_collection_endpoint and data_collection_rule.

Azure Monitor retires the HTTP Data Collector API on 14 September 2026. Its replacement, the Logs Ingestion API, needs a data collection endpoint and a data collection rule, and neither exists in this library yet.

The rule module takes a list of custom streams. Each stream gets a stream declaration describing the incoming payload plus a data flow with a transform into an existing custom table. That way a caller can move a table off the Data Collector API while keeping its column names, so the workbooks and alert rules that query those columns keep working.

Both modules pass terraform fmt -check and validate/validate.sh against azurerm 3.117.1, and they are already running on the VWT Telecom dev environment with 20 streams.

[nbroers-hanab]

Looks good. Both modules follow the repo layout (main/variables/outputs, required_version ~> 1.12, azurerm ~> 3.117, backend + provider block so validate.sh can override them) and the resource labels match the naming used elsewhere in modules/azure. Lint and Validate are green, and I checked the deployed pair in the Telecom dev environment: dce-hti-int-platform-dev is Succeeded with both endpoints populated, and dcr-hti-int-platform-dev has 20 stream declarations plus 20 matching data flows into the logAnalytics destination, with no kind set, which is right for direct ingestion.

A few non-blocking notes for a follow-up:

• The constraints in the streams description (name must start with Custom-, output stream must point at an existing table) and the allowed column types are not enforced by validation blocks, so a typo surfaces as an Azure error at apply instead of at plan. An empty streams list runs into the provider's minimum of one data_flow for the same reason.
• data_flow is a list in the provider, and iterating a map gives lexicographic order, so adding a stream that sorts early reshuffles the indices in the plan output. Cosmetic only, the result is the same.
• transform_kql and output_stream could be optional(string) (with transform_kql defaulting to "source") now that the modules require Terraform 1.12, which saves callers from passing explicit nulls.
• Consumers still need a Monitoring Metrics Publisher assignment on the rule before they can send anything. Worth calling out in the consuming repo, since it is outside the scope of these modules.