feat(background-task): add 4 background task tools

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src/tools/background-task/index.ts

@@ -0,0 +1,9 @@
+export {
+  createBackgroundTask,
+  createBackgroundStatus,
+  createBackgroundResult,
+  createBackgroundCancel,
+} from "./tools"
+
+export type * from "./types"
+export * from "./constants"