feat(packages/stdlib): add promise types

packages/stdlib/src/types/ts/index.ts

@@ -1,3 +1,4 @@
-export * from './string';
+export * from './array';
 export * from './function';
-export * from './array';
+export * from  './promise';
+export * from './string';

packages/stdlib/src/types/ts/promise.ts

@@ -0,0 +1,4 @@
+/**
+ * Represents a value that may be a promise.
+ */
+export type MaybePromise<T> = T | Promise<T>;