ui(connections): migrate connection forms to QueryaDialogCard (#520)

[ZhuchkaTriplesix]

Summary

• Migrate PG / MySQL / Mongo / Redis / SQLite / extension connection form shells to QueryaDialogCard
• Keep existing constraints and muted border; drop raw Container + ClipRRect popover chrome

Closes #520

Test plan

• Open create + edit for each built-in driver and an extension driver — layout/chrome match other dialogs
• Save / Cancel / Test still work
• No text bloat / overflow in dense forms
• flutter test test/features/postgresql/postgresql_connection_form_test.dart