feat: add @hey-api/angular-resource plugin with Angular resource generation
- Introduced the @hey-api/angular-resource plugin to facilitate Angular resource generation.
- Implemented configuration options for generating resources as classes or functions.
- Created necessary types and interfaces for the plugin.
- Developed the plugin handler to generate Angular services based on SDK operations.
- Added auto-generated resource methods for Pet, Store, and User entities.
- Updated the plugin configuration map to include the new angular-resource plugin.
- Removed deprecated httpResource option from the client-angular plugin.