Some functions split to be more cohesive, custom PostSteps are
stored as pointers to allow their retrieval and parameters passing
in runtime if needed (some extra work is dropped and TBD
when needed)
The only place where appDB is used in wallet is activity,
which refers to `keycards_accounts` table. So a temporary
table `keycards_accounts` is created in wallet db and updated
before each activity query.