Lints for banning usage of Flutter's showDialog/showBottomSheet APIS

[ueman]

Since the wolt_modal_sheet is a replacement for dialogs and bottom sheets, we should provide a lint that bans Flutter's APIs for showing dialogs and bottom sheets, and suggests to use wolt_modal_sheet instead.

This could be achieved via DCM's banned-usage lint.

Some APIs that should be banned:

• https://api.flutter.dev/flutter/material/showDialog.html
• https://api.flutter.dev/flutter/material/ScaffoldState/showBottomSheet.html
• https://api.flutter.dev/flutter/material/showModalBottomSheet.html
• maybe some others?