Feature Request: Support Multiselect for rio.Dropdown

[Sn3llius]

Summary:

It would be great to have multiselect support for the rio.Dropdown component in Rio. This feature would enhance the usability and flexibility of dropdown menus by allowing users to select multiple options at once.

Detailed Description:

Currently, the rio.Dropdown component supports single selection, which is sufficient for many use cases. However, there are scenarios where selecting multiple items from a dropdown is necessary. Adding multiselect functionality would greatly benefit users who need to choose several options without having to use multiple dropdown components or creating their own suboptimal solutions.

Proposed Solution:

• Implement a multiselect mode for rio.Dropdown that can be activated through a new attribute (or potentially as a separate component).
• Ensure that selected items are displayed clearly within the dropdown, with an option to deselect each item.
• Provide keyboard and mouse support for selecting and deselecting multiple items.
• Allow for custom styling to accommodate different design requirements.
• Include support for components like checkboxes for selecting items

Benefits:

• Improved user experience by reducing the need for multiple dropdowns.
• Increased flexibility in form design and data selection.
• Enhanced productivity for users needing to make bulk selections.

Additional Context:

Multiselect dropdowns are common in many applications and frameworks, such as React and Flutter. Bringing this feature to Rio will align it with modern UI component standards and fulfill the needs of more complex user interactions.

Related PR:

#50

Looking forward to the discussion and feedback from the community!