[feature] allow modifying jitter at a per-watch level

[RoguedBear]

Version and OS

0.45.22/docker

Is your feature request related to a problem? Please describe.

Recently I created a watch to get updates for something very time sensitive.
Since i overrode the global time between checks to 5 minutes, I expected the watch to alert me of changes quickly.

It wasn't until i manually checked the target website when i got to know the page was updated with new information.

I was wondering why didn't changedetection alert me earlier. I noticed that the "last checked time" shown in the dashboard was 36 minutes ago when it should have been less than 5 minutes (because time b/w check was set to 5 minutes)

I eventually figured out it was because in the settings page i kept the jitter value to 1 hour. I did not remember i even set this value.

My default global settings are very relaxed to lower chances of my ip getting rate limited. 12 hours for checks and then a 1 hour jitter. Obviously i override the time between checks when needed for a specific site but i forgot about the existence of a jitter value until this happened

So now if i have to create a time sensitive check i would also have to adjust the global jitter.

Describe the solution you'd like

Just like how we have an option to override time between checks at a per-watch level, have an option to configure the jitter as well.

Describe the use-case and give concrete real-world examples

The site i was monitoring was booking status of a friend's train tickets a few hours before departure. (dont worry they decided to cancel the tickets instead since it wasn't confirmed. 😺 )

Additional context

NA