Update lit-starter-ts to lit-next

* Upgrades the source to work with lit-next
* Aligns the linting and formatting rules/settings & ignores with the monorepo
* Upgrades to the same version of typescript and tsconfig settings as the monorepo
* Upgrades the test runner from karma to web-test-runner
* Upgrades the dev server from es-dev-server to @web/dev-server

src/my-element.ts

@@ -12,7 +12,8 @@
  * http://polymer.github.io/PATENTS.txt
  */
 
-import {LitElement, html, customElement, property, css} from 'lit-element';
+import {LitElement, html, css} from 'lit';
+import {customElement, property} from 'lit/decorators';
 
 /**
  * An example element.

src/test/my-element_test.ts

@@ -1,4 +1,5 @@
 import {MyElement} from '../my-element.js';
+
 import {fixture, html} from '@open-wc/testing';
 
 const assert = chai.assert;