Enabling chip register read via FrontEndConnectivity implementation

This merge request is prepared primarily to work for FELIX pixel firmware where data and service frames are split into two separate channels. Hence, it becomes challenging to read chip register data during the scan. This is part of development for issue - 233

In this new implementation, an independent register channel is added in the FrontEndConnectivity class, which can then be passed through the chip connectivity file. The default value of register channel (for ex, for YARR firmware) is same as the data channel. Currently, this has been tested to work with RD53B chips (SCC and module) on FELIX setup while implementation for Itkpixv2 chips will follow soon.