updated migrations to comply with validations, added guidance-guidance_groups many to many relationship back in for migration

Moved orcid_id from users table to user_identifiers. Added option_based flag to question_formats. switched Object.const_defined to table_exists checks in db migrations because rails loads references to classes on demand so the objects are likely not defined when the migrations run. safer to check for the underlying table's existence

Added checks to migration files that manipulate data to make sure that the model they are attempting to access is defined in the current codebase

re-aranged migraitons so that bit_flags for roles happens before foreign keys