Improve CSV upload experience

• The current CSV upload experience is form-based and overwhelming to users. The user must navigate the form (many options of which are unclear), upload, and hope the product parsed their data correctly.

• The current CSV upload requires the user to have connected a database first - this makes it so that users who want to use thhttps://preset.aha.io/features/PROD-264e CSV to test data before connecting their data are unable to.

Revamp CSV upload experience to put less burden on the user and/or presents a more visual parsing experience that users can use to test data before connecting their own data.