SQL Server: Scaffold HasTrigger if the table contains triggers

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Since #27372, SaveChanges fails by default on SQL Server for tables with triggers. We could detect triggers when scaffolding and scaffold HasTrigger to make the database-first story smoother. This may be a bit tricky since HasTrigger is on TableBuilder rather than directly on EntityTypeBuilder (not sure if we already have the infra for scaffolding that).

Raised by @ErikEJ in ErikEJ/ErikEJ#1 (comment)