feat: Added hint_timeout option to hide hints after a delay

[Sawangg]

@m4xshen This PR adds a hint_timeout option with a default value of 5000 to hide hints after a delay.
This addresses issue #82. This implementation resets the timeout back to its original value if a new hint comes in before the last timeout was executed.

Feel free to edit the default value if 5000 is not to your taste but it seems like a good middle ground in my tests.

[m4xshen]

Hi @Sawangg,

Thanks for picking up this issue!

I tested it out and found that your implementation doesn't work with nvim-notify. Instead of clearing the last notification, it sends a new blank notification, as shown here:

The primary goal of #82 is to work with nvim-notify, as the UI-style notification is annoying if it stays too long. For native text notifications, a timeout mechanism isn't needed since it doesn't block anything.

Sorry for the unclear issue description. If you have any further questions, feel free to ask!