Convert to ESModules & export everything (#1)

* 🔧 Use Node16 module and moduleResolution

* 🔧 Update package.json to support Node16 module and moduleResolution

* 🚚 Export everything and fix jsdocs

* 🚚 Rename file to `token-counts` to align it with the unit test file

* ✅ Fix tests by using Vitest instead of Jest

* ✅ Fix end-to-end tests in Vitest

* ♻️ Make temporary variable for promptTokensEstimate in tests

* 🧑‍💻 Add declarationMap to tsconfig.json

Author: NatoBoram

README.md

@@ -40,11 +40,11 @@ const estimate = promptTokensEstimate({
 
 ## Development and testing
 
-Built in TypeScript, tested with Jest.
+Built in TypeScript, tested with Vitest.
 
-```bash
-$ npm install
-$ npm test
+```sh
+npm install
+npm test
 ```
 
 When adding new test cases or debugging token count mismatches, it can be helpful to validate the estimated tokens in the tests against the live OpenAI API. To do this: