DAQ path does not use SLink

Current L1DataAggregator uses IPBus for readout, thus is limited to 16 links, and struggle with timing closure

changed milestone to %CHARM Test Beam

I made a patch of L1DataAggregator where the slink stream from DAQ Path is exposed and there is a backpressure input.

This could be a first step towards the solution.

added Medium Priority label

added High priority label and removed Medium Priority label