Add toolbars and improvements for screen reader for chat messages

[adamsamec]

Description of changes

This PR updates the prototype for the enhanced accessible experience of the Chat component.

additions compared to the previous version

• When user drills into a focused chat message with the Enter key, two toolbars (for message reactions and for reply/message options) are now available, which can be navigated using the Tab key. The message content is the third Tab stop, and interactive elements (such as links) within the message content are the subsequent Tab stops.
• The messages now include date and time, details (edited state), and a smile reaction.

Features to be worked on with JAWS

• The enhancement should enable JAWS screen reader users to automatically switch to the virtual cursor mode after drilling into message with the Enter key and focusing the message content with the Tab key. The virtual cursor mode should switch back to the application mode once the user tabs out of the message content.
• Additionally, once the user focuses the message content with the Tab key, the virtual cursor navigation should be confined to the message content, i. e., trapping the virtual cursor. However, the tabbing should not be confined, letting the user to tab out of the message content. Also the Escape key should switch back to the application mode as the message popover closes.
• The message content can be focused directly via the Control + Enter keyboard shortcut pressed on a focused message.