[ENHANCEMENT]: make pages perform less queries by performing more calculations in backend

[jessevz]

Description

Currently the task page in the new webUI will perform a lot of queries to get the chunks. It needs this in order to calculate the amount of agents and taskstatus. In order to make the frontend perform queries, the task api can add this data so that frontend doesn't need to calculate it.
Possibly this is also needed for speed which is only visible on the detail page but that depends if the data of the detail page is already loaded at that point. The same goes for agents page and possibly other pages aswell.

• task page (amount of agents and taskstatus)
• agent page