Add TS tests tooling (#661)

* install test dependencies

* change config for tests

* fix linter failing tests

* add basic test file

* add custom element registration to test

* update dependencies

* add jest config file

* fix test calls on makefile and minor fix on test

* update local npm version

* clean testm file

pyscriptjs/tests/unit/pyrepl.test.ts

@@ -0,0 +1,16 @@
+import 'jest';
+import { PyRepl } from '../../src/components/pyrepl';
+
+customElements.define('py-repl', PyRepl);
+
+describe('PyRepl', () => {
+    let instance: PyRepl;
+    beforeEach(() => {
+        instance = new PyRepl();
+    });
+
+    it('should get the current Repl to just instantiate', async () => {
+        expect(instance).toBeInstanceOf(PyRepl);
+    });
+
+});