feat(a11y): add explicit FocusTraversalGroup to multi-section connection dialogs

[ZhuchkaTriplesix]

Motivation & Goal

Improve keyboard accessibility (A11y) and Tab traversal order in dense, multi-section connection setup dialogs.

Proposed Scope

• Wrap connection form containers and expandable option sections (SSL Certificates, SSH Tunneling, Driver Options) with FocusTraversalGroup(policy: WidgetOrderTraversalPolicy()).
• Prevent erratic Tab / Shift+Tab focus jumps into collapsed or secondary sections.
• Ensure focus moves deterministically from Host -> Port -> Database -> Username -> Password -> Action Buttons.
• Add widget tests validating focus order during Tab key presses.