feat: Typescript for API layer (#817)

Co-authored-by: Philip Korsholm <88927411+pKorsholm@users.noreply.github.com>
Co-authored-by: Zakaria El Asri <33696020+zakariaelas@users.noreply.github.com>
Co-authored-by: Kasper Fabricius Kristensen <45367945+kasperkristensen@users.noreply.github.com>
Co-authored-by: Philip Korsholm <philip.korsholm@hotmail.com>
Co-authored-by: Sebastian Rindom <seb@medusa-commerce.com>

packages/medusa-core-utils/tsconfig.json

@@ -0,0 +1,22 @@
+{
+  "compilerOptions": {
+    "lib": ["es5", "es6"],
+    "target": "es5",
+    "outDir": "./dist",
+    "esModuleInterop": true,
+    "declaration": true,
+    "module": "commonjs",
+    "moduleResolution": "node",
+    "emitDecoratorMetadata": true,
+    "experimentalDecorators": true,
+    "sourceMap": true,
+    "noImplicitReturns": true,
+    "strictNullChecks": true,
+    "strictFunctionTypes": true,
+    "noImplicitThis": true,
+    "allowJs": true,
+    "skipLibCheck": true
+  },
+  "include": ["./src/**/*"],
+  "exclude": ["./dist/**/*", "./src/__tests__", "node_modules"]
+}