build: Ephemeral environments for PRs via slash command (#13189)

* First pass at ephemeral env, new Docker ci target

* Add service checks, get public IP

* Separate issue_comment and workflow_run jobs

* Refactor workflows

* Adjust comment author association

* Checkout code

* Fix image name, manage service desired task count

* Use merge commit sha

* Fix IP output, add failure comment

* Refactor comment parsing & env spinup

* Check container image publish status

* Parse AWS account ID from registry URL

* Use PR number rather than variable merge commit SHA for image tag

* Fix docker push conditional

* Push multiple tags to ECR

* Fix comment author check

* Refactor comment body check

* Provision service with active task to get correct IP

* /testenv up

* Add @mentions to PR comments, env var cleanup

.github/workflows/ecs-task-definition.json

@@ -0,0 +1,51 @@
+{
+    "containerDefinitions": [
+        {
+            "name": "superset-ci",
+            "image": "apache/superset:latest",
+            "cpu": 0,
+            "links": [],
+            "portMappings": [
+                {
+                    "containerPort": 8080,
+                    "hostPort": 8080,
+                    "protocol": "tcp"
+                }
+            ],
+            "essential": true,
+            "entryPoint": [],
+            "command": [],
+            "environment": [
+                {
+                    "name": "SUPERSET_LOAD_EXAMPLES",
+                    "value": "yes"
+                },
+                {
+                    "name": "SUPERSET_PORT",
+                    "value": "8080"
+                }
+            ],
+            "mountPoints": [],
+            "volumesFrom": [],
+            "logConfiguration": {
+                "logDriver": "awslogs",
+                "options": {
+                    "awslogs-group": "/ecs/superset-ci",
+                    "awslogs-region": "us-west-2",
+                    "awslogs-stream-prefix": "ecs"
+                }
+            }
+        }
+    ],
+    "family": "superset-ci",
+    "taskRoleArn": "ecsTaskExecutionRole",
+    "executionRoleArn": "ecsTaskExecutionRole",
+    "networkMode": "awsvpc",
+    "volumes": [],
+    "placementConstraints": [],
+    "requiresCompatibilities": [
+        "FARGATE"
+    ],
+    "cpu": "512",
+    "memory": "1024"
+}