Update dependencies and scripts in adapter-electron for improved functionality

- Added `nodemon` and `wait-on` as dependencies in the electron example's package.json for better development experience.
- Updated the `dev` script to utilize `wait-on` for ensuring the Vite server is running before starting Electron.
- Enhanced the README.md with clearer instructions and examples for configuring the adapter and its options.
- Removed the `functions` option from the TypeScript definition to simplify the interface.
- Cleaned up unused imports in setupHandler.js to streamline the code.

packages/adapter-electron/index.d.ts

@@ -6,12 +6,6 @@ export interface AdapterOptions {
    * @default 'out'
    */
   out?: string;
-  
-  /**
-   * Directory name for the protocol handler functions
-   * @default 'functions'
-   */
-  functions?: string;
 
   /**
    * Whether to precompress static assets