calendar component

[not-lain]

in this pull request you will find

• changed the grcalendar to calendar
• a working demo that handles type ="date" and "datetime-local"
• error handling and big changes to the calendar.py

[not-lain]

closing this because i can't figure out how to fully integrate the calendar componenet as a gradio componenet.
these are interesting resources that might help :

• https://svelte.dev/repl/77f694a1851d464b85b382f4f152cb8e
• Provide a way to dynamically set input type (with or without two way binding) sveltejs/svelte#3921
  best of luck 🍀