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>

.eslintrc.js

@@ -23,18 +23,31 @@ module.exports = {
     node: true,
     jest: true,
   },
+  ignorePatterns: [`**/models`, `**/repositories`],
   overrides: [
     {
       files: [`*.ts`],
       parser: `@typescript-eslint/parser`,
       plugins: [`@typescript-eslint/eslint-plugin`],
       extends: [`plugin:@typescript-eslint/recommended`],
+      rules: {
+        "@typescript-eslint/explicit-function-return-type": ["error"],
+        "@typescript-eslint/no-non-null-assertion": ["off"],
+      },
     },
     {
-      files: ["**/api/**/*.js"],
+      files: ["**/api/**/*.js", "**/api/**/*.ts"],
       rules: {
         "valid-jsdoc": ["off"],
       },
     },
+    {
+      files: ["**/api/**/*.ts"],
+      rules: {
+        "valid-jsdoc": ["off"],
+        "@typescript-eslint/explicit-function-return-type": ["off"],
+        "@typescript-eslint/no-var-requires": ["off"],
+      },
+    },
   ],
 }