wxGUI: Refactored try-except block to be more robust in dialogs.py

[arohanajit]

Description

This PR is more of a suggestion since I thought this would be a better way to handle this instead of a try-except block. It modifies the GetSQLString method in the DisplayAttributesDialog class to improve how it retrieves values from widgets. The changes make the code more robust and explicit in handling different widget types.

Changes

• Replace bare except clause with explicit checks for GetValue() and GetLabel() methods
• Add error handling for widgets that have neither method

Reason for Changes

The original code used a bare except clause to handle potential AttributeErrors when trying to call GetValue() or GetLabel() on widgets. This approach was not robust and could potentially hide unexpected errors. The new implementation explicitly checks for the presence of these methods and raises an AttributeError if neither are present.