Draft: FLX-2533 strips DCS data path

Code for identifying and copying register reads to a separate axis FIFO functional. Needs to testing, especially with bad data and Reverted DecEgroup_8b10b_tb.vhd to pre strips-extras version, adding compatibility mods only. Added Strips specific TB (as DecEgroup_8b10b_Strips_tb.vhd) to allow DUT instantiation with generics set as per strips.

Closes FLX-2533