Tests for region-specific GMM behavior

Requires updating all *-inputs.csv with flag column. This could likely just be empty.
See also line 152 of GmmTest

added 2023 GMM labels

changed the description

changed title from Tests for simulation informed GMMs to Tests for region-specific GMM behavior

changed the description

changed milestone to %Beta release of CONUS NSHM

ALthough it looks like flags may go away, this was resolved in !334 (merged) and related MRs

closed