Improve member information loading

[timonla]

In the old version the injection of the member information into the data-table was executed in parallel. Not sure if it would just cause chaos or actually improve the user experience.
In any case there should be some indication if member information is loading or not.

[timonla]

To clarify, the requests are already parallelized. If we just insert all elements from the beginning and give them some loading content until we fill them with the correct values or N/A if there is no data for this user, this should work as before.

[marcquark]

i'd like to work on this, but i think open PRs should be merged first and refactoring should be finished, otherwise we'll go through a lot of rebasing/cherrypicking
do u agree?