Added keyboard support for DxcToast

[Mil4n0r]

Checklist
(Check off all the items before submitting)

• Build process is done without errors. All tests pass in the /lib directory.
• Self-reviewed the code before submitting.
• Meets accessibility standards.
• Added/updated documentation to /website as needed.
• Added/updated tests as needed.

There was no proper interaction using keyboard with the Toast component. Now there should be no issues dealing with the focus using tab.

[Jialecl]

The only improvement that I can think of is to be able to focus in other tost components that are on the same queue.