Add vite build (#53)

* Add vite build - baseline

* Fix build output folder structure

Matches pre-vite output

* Fix litegraph errors introduced by vite process

- Remove pre-written encapsulating iife (one is injected by vite)
- Replace all references to the global "this" with globalThis

vite.config.mts

@@ -0,0 +1,21 @@
+import { defineConfig } from 'vite'
+import path from 'path'
+
+export default defineConfig({
+  build: {
+    lib: {
+      entry: path.resolve(__dirname, 'src/litegraph.js'),
+      name: 'litegraph.js',
+      // TODO: Below workaround ensures output matches pre-vite format.  Should be removed.
+      fileName: (moduleFormat, entryAlias) => 'src/litegraph.js',
+      formats: ['iife']
+    },
+    minify: false,
+    sourcemap: true,
+    rollupOptions: {
+      // Disabling tree-shaking
+      // Prevent vite remove unused exports
+      treeshake: false
+    }
+  },
+})