Enable filesystem watch for development

[mostafa]

• [ ] Watch changes to Go files
• [ ] Rerun GatewayD on change
• [ ] Regenerate stubs (make gen)
• [ ] Recompile and reload plugins

Related

• #297
• #300

Resources

• https://github.com/cosmtrek/air
• https://github.com/fsnotify/fsnotify
• https://github.com/radovskyb/watcher
• https://github.com/silenceper/gowatch
• https://github.com/mitranim/gow
• https://github.com/agschwender/autoreload
• https://github.com/vrongmeal/leaf
• https://github.com/makiuchi-d/arelo
• https://github.com/ailncode/af
• https://github.com/thiagozs/go-reload
• https://github.com/0del/ron
• https://github.com/roger-russel/fresher
• https://github.com/whiteCcinn/daemon