Warn users about impact of `dataflow reset`

[travjenkins]

Please propose features in the Discussions area as an idea
When a user is about to publish something with dataflow reset populated we need to inform them about the impact.

“Data-flow reset truncates your collections, which will drop data from any downstream delta-updates materialializations” or similar ?

https://estuaryworkspace.slack.com/archives/C02G25WJCNS/p1768403003840249

[dyaffe]

I'd modify it slightly to "Dataflow reset truncates your collections, which will drop data from any downstream destinations. Selecting “Incremental Backfill” will maintain existing data which may be desirable if delta updates materializations exist downstream."