Backport of MR !320 !319 !316, updates to the slow controls SDF to not constrain monitored PVs to a specific prefix

• Remove the prefix from the parsing of the req file.
• Add a target to build the sequencer to the cmake, for testing purposes.
• Updates the parsing of req and snap files to explicitly skip burt headers.

This is a back port (cherry pick) of commits that went into master.

changed milestone to %4.2.8

assigned to @erik.vonreis and @ezekiel.dohmen

merged

mentioned in commit ff6fbcc3