BrainScaleS: Update software state

We introduce 5.0-rc1 which is 4.0-rc2 + a few backported build changes that enables building on non-x86 architectures. This update introduces compile-time switches to disable building parts of the low-level software stack which can be skipped for EBRAINS operation; in particular, the communication modes for non-quiggeldy (the experiment service) communication with the neuromorphic system are now disabled conditionally.