Add threshold tracking for auras

[Auliyaa]

Is your feature request related to a problem? Please describe.
I'm playing restoration druid and I setup several auras to follow my hots on group members like so:

I would like to be able to change my aura indicator in some way when the time remaining on the HoT goes below a certain threshold.
Basically I'd like to flash my indicator in some way when the remaining time goes below 30% of the original duration:

For reference, this corresponds to the time where refreshing a HoT carries over the remaining duration of the previous application.

Describe the solution you'd like

I'd like to be able to setup the border color and time threshold when configuring the Aura filter in the Filters setting panel.

Describe alternatives you've considered
I've looked over for WeakAuras but this gets annoying when you have to follow multiple targets. Having this at the same place as my already exiting aura tracker would really be nice to have.

Additional context
I'm open for code proposal and I've already tried to modify the oUf_AuraFilters.lua but without success. If anyone could give me some kind of indication on where I should look first I'd gladly take a look a provide a patch here.