Remove permmclient code

[SebastianSchildt]

We still have some old code rom an earlier prototype getting tokens from a backend i.e. https://github.com/eclipse/kuksa.val/blob/12eed6ef1bb56cb3913495567dc13dd208d3f3a2/src/permmclient.cpp
(see also kuksa-authorize command in command processor)

It is neither tested, nor generally usable, and thus should be removed

[SebastianSchildt]

Was fixed by #198