Make pulse_lib metadatable

Created by: NicoHendrickx

I think it would be nice to make the pulse_lib either a QCodes Metadatable and/or provide metadata function, such that some key settings can be snapshotted when performing a measurement. These would be things like the pulse_lib settings such as attenuation/gate_map/virtual_gate_matrices.

Additionally I believe it could be very valuable to also save the waveform of an experiment when performing the experiment. It would be best to compile this into some way (maybe use the original input parameters?), so that we don't have to save the actual wave form data, but can rather save something like: "Voltage x for y time, ramp between a and b in y time" etc. I have thought about this for a bit, but haven't decided what would be the best implementation, but regardless believe that some form of logging/metadata on this can be very valuable for interpreting data in the future.