build(vite): replace webpack with Vite, add Typescript (#1594)

BREAKING: mixins are no longer exported from the index (and will likely be converted to hooks)

tsconfig.app.json

@@ -0,0 +1,13 @@
+{
+  "extends": "@vue/tsconfig/tsconfig.web.json",
+  "include": ["env.d.ts", "src/**/*", "src/**/*.vue"],
+  "exclude": ["tests"],
+  "compilerOptions": {
+    "composite": true,
+    "baseUrl": ".",
+    "paths": {
+      "@/*": ["./src/*"],
+      "@tests/*": ["./tests/*"]
+    }
+  }
+}