feat: Add support for dialog tag and create example templates

[0yeifer]

New Dialog Block Templates Added
Two native <dialog> templates are now available:

1. Dialog Show:
   • Contains a trigger button with onclick="<dialogId>.showModal()"
   • Modal includes a simple form and three action buttons and one required text input:
     • Validate and Close (form submission via method="dialog" validating input required)
     • Non-Validate Close (submit without validation using attribute formnovalidate)
     • JS Close (native call to close() method via onclick="<dialogId>.close()")
   • Supports native features:
     • Esc key cancellation

2. Dialog Modal:
   • Open-by-default dialog (open attribute) with confirmation button
   • Demonstrates attribute-driven visibility

Key Implementation Notes:

• Zero external JS dependencies - uses native HTMLDialogElement methods via ID references
• Templates maintaining Frappe Builder low-code philosophy

Next Steps:
There is an editor/published view visibility discrepancy that remains unresolved due to the display handling.
Awaiting feedback, I will keep an eye on the PR for any necessary changes.

[0yeifer]

Hello @surajshetty3416 Is there any issue with this PR or something that needs to be changed/improved? I could work on any corrections if needed.