Recent changes regarding obs_decam

With the merge of DM-5899, processing DECam raw data with the Community-Pipeline calibration products will require a config override and retarget the ISR to DecamCpIsrTask. The CP bias and flat dataset types are renamed to cpBias and cpFlat. For convenience an example config file is added in obs_decam/config/processCcdCpIsr.py. The dataset types bias and flat are then used by the LSST-produced calibration products (through constructCalibs.py) and that is the new default. Also, the old usage of the dataId key side/ccd is cleaned and removed. See DM-5899 for more details.