Add unit testing support with vitest (#18)

* update loose files and add vitest

* update test scripts

* more support for vitest

* more test support

* update vscode settings

.eslintrc

@@ -0,0 +1,17 @@
+{
+	"env": {
+		"browser": true,
+		"es2021": true
+	},
+	"parserOptions": {
+		"ecmaVersion": "latest",
+		"sourceType": "module"
+	},
+	"overrides": [
+		{
+			"files": ["src/**/*.ts"],
+			"extends": "eslint:recommended"
+		}
+	],
+	"rules": {}
+}