feat(iot): Add IAction

This change adds `IAction` to aws-iot for preparing to implemamt AWS IoT Rule
actions.

packages/@aws-cdk/aws-iot/lib/action.ts

@@ -0,0 +1,24 @@
+import { CfnTopicRule } from './iot.generated';
+import { ITopicRule } from './topic-rule';
+
+/**
+ * An abstract action for TopicRule.
+ */
+export interface IAction {
+  /**
+   * Returns the topic rule action specification.
+   *
+   * @param rule The TopicRule that would trigger this action.
+   */
+  bind(rule: ITopicRule): ActionConfig;
+}
+
+/**
+ * Properties for an topic rule action
+ */
+export interface ActionConfig {
+  /**
+   * The configuration for this action.
+   */
+  readonly configuration: CfnTopicRule.ActionProperty;
+}

packages/@aws-cdk/aws-iot/lib/index.ts

@@ -1,3 +1,4 @@
+export * from './action';
 export * from './iot-sql';
 export * from './topic-rule';