Support skipping conflicting rows during CSV import

When importing CSV data through Supabase Studio, some rows may conflict with existing primary key or unique constraint values. In cases where a CSV contains both new rows and rows that already exist in the table, it would be helpful if the non-conflicting rows could still be imported while the conflicting rows are skipped. This would be similar to PostgreSQL's: I couldn't find an equivalent option in the Studio CSV import flow, so I wanted to suggest it as a possible enhancement. It would be helpful to have an option in the CSV import UI such as: • Skip conflicting rows • Continue importing the remaining valid rows when a primary key or unique constraint conflict occurs • Report the number of skipped rows after the import completes Conceptually, this could behave similarly to: As a possible future enhancement, users could also be allowed to choose a specific unique constraint as the conflict target. However, simply supporting …