feat(plugins): use @tauri-apps namespace on NPM (#368)

Co-authored-by: Amr Bashir <amr.bashir2015@gmail.com>

plugins/upload/README.md

@@ -51,7 +51,7 @@ fn main() {
 Afterwards all the plugin's APIs are available through the JavaScript guest bindings:
 
 ```javascript
-import { upload } from 'tauri-plugin-upload-api'
+import { upload } from '@tauri-apps/plugin-upload'
 
 upload(
     'https://example.com/file-upload'

plugins/upload/package.json

@@ -1,5 +1,5 @@
 {
-  "name": "tauri-plugin-upload-api",
+  "name": "@tauri-apps/plugin-upload",
   "version": "0.0.0",
   "description": "Upload files from disk to a remote server over HTTP.",
   "license": "MIT or APACHE-2.0",