Implement picker title and picker description

[koukibadr]

• Create pickerTitle and pickerDescription instead of title, description, titleStyle and descriptionStyle
• Mark title, description, titleStyle and descriptionStyle as deprecated
• Use stack widget to display title and close icon in same line rather than columns and rows, for better alignement
• Change titleAlignment type to Alignment instead of MainAxisAlignment
• Update bottom picker examples code snippets