feat(collectionagent): add ecs ec2 collection agent

[Nageshbansal]

Features

• Adds the ecs/ec2/terraform CollectionAgent casting: a DAEMON service running one stock contrib collector per container instance on host networking, with OTLP, hostmetrics, docker_stats and filelog.
• Delivers the collector config through AWS AppConfig: a hosted configuration version, an agent sidecar that writes it into the task, and a config digest on the task definition so a changed config replaces the task rather than being rewritten under a running collector.
• Gives container logs their identity from the four ECS labels docker's json-file driver copies into each line, and carves container.id out of the file path. A task definition without the labels option still produces records, carrying container.id alone.
• Detects env and ec2 only. On a DAEMON the ecs and docker detectors answer for the collector's own task and would stamp every container's telemetry with the agent's identity.
• Collects the instance's own logs (/var/log/messages, /var/log/secure, /var/log/ecs/*.log) as service.name=ecs-host.
• Runs the agent's own two containers on the none log driver, so the collector does not tail itself through the docker-containers mount.
• Creates the task and execution roles, or references the ARNs stated on the casting and creates neither.
• Reads four annotations: foundry.signoz.io/ecs-region, ecs-cluster-arn, ecs-task-role-arn, ecs-task-execution-role-arn.
• Ships an example whose README covers the labels block every task definition needs for its logs to carry a service name, the patch that swaps the agent's own log driver for awslogs, and that awslogs containers are out of scope.

Tests

• Template tests across both role branches: AppConfig delivery, the DAEMON service settings, resource names, the detector list, and that the label lifts tolerate a task definition that carries no labels.

Related: https://github.com/SigNoz/platform-pod/issues/1973