Add global “Jump to Next Unread Message” button + shortcut

[lual]

Feature Request Description:

Currently, Element users face difficulty navigating unread messages because unread indicator dots are scattered across multiple rooms, spaces, and threads.
I propose adding a global “Jump to Next Unread” feature with the following characteristics to improve navigation and usability:

• A global button accessible from anywhere in the app to jump to the next unread message.
• A keyboard shortcut for quick access.
• The jump order follows the chronological order of when unread messages were received, regardless of room or space.
• When jumping to an unread message, the message could have enhanced visual highlighting (e.g., a bright background or border) to make it clearly visible.

This improvement will greatly enhance user experience, especially for users active in multiple rooms and threads.

Thank you for considering this valuable enhancement.