fix: create jest.config.js for clients (smithy-lang#291)

Author: trivikr

smithy-typescript-codegen/src/main/resources/software/amazon/smithy/typescript/codegen/jest.config.js

@@ -1,7 +1,4 @@
-const base = require("../../jest.config.base.js");
-
 module.exports = {
-    ...base,
-    // Only test cjs dist, avoid testing the package twice
-    testPathIgnorePatterns: ["/node_modules/", "/es/"]
+  preset: "ts-jest",
+  testMatch: ["**/*.spec.ts", "!**/*.browser.spec.ts", "!**/*.integ.spec.ts"],
 };