Migrate BExt and IDE dismissal to temporary settings

Created by: philipp-spiess

This PR addresses a further issue with the current BExt and IDe CTAs: When the banner is dismissed, we will currently only store it inside localStorage. To remember this config per-user, we should instead use temporary settings (for logged out users, the behavior is the same).

Test plan

I made sure that the preference is now saved in GraphQL: