feature: remove delay when clearing all notifications

[rubiin]

When having 50+ notifications, clicking the clear all button takes some time before it does the job.

This was because we were adding a delay with settimeout of 100 ms .
This makes the clearall instant which is a better UX similar to other implementations like in swaync

[Jas-SinghFSU]

I'm not a fan of the delay either ideally it should be MUCH lower but this is something you have to do to prevent crashes in AGS. Notice the clearDelay property on the AGS documentation https://aylur.github.io/ags-docs/services/notifications/.

For some users this number has to be even higher. If we want to remove it, we can add an option to let the user define the delay amount and add a warning below the settings that "Setting this value too low may crash AGS".

[rubiin]

Looks like this PR still needs some work. I will try to add in the option by tomorrow

[rubiin]

Updated the setting widget to include the delay with the initial value as 100 ms.

[Jas-SinghFSU]

That's for the wonderful contributions! ❤️