Nope, imo there wont ever be any addon supporting any other (like 10000) addon's SavedVariables.
The addons need to provide this settings on their own.
All addons I know that tried to achieve this failed and crashed more than that they worked. Forget that idea please, it's way to much work as you would need to support like 20 different ways of saving the data, and eacha ddon behaves differently.
IF you want toa chieve this you need to create your settings for the addons, then logout. Go to live/SavedVariables/<addonname>.lua and save that file somewhere as backup.
Create yourself a batch file (e.g. farm.bat) and add the backuped files you want to copy over to your live/SavedVariables folder for your purpose (e.g. "farming").
Login again and setup your addons for "combat", logout and backup etc, do the same for "dungeon" and so on.
You can use the batch files then as you are at the character selection screen to change the SavedVariables. But as the contents of the SV might need to update you would have to backup the files each time after logout again, manually.
If you do not have any software which is able to do this for you, + it needs to be backuped to the correct folders (e.g. live/SVbackup/farm, live/SVbackup/dungeon, ...).
That's only an idea.