fix: lib/sh/db.sh: psql(): added $output_data switch analogous to what mysql() has. this causes query results of eg. void-returning functions to be correctly filtered by the logging mechanism, rather than output to stdout.

fix: lib/sh/db.sh: psql(): verbosity=0 (errors only) mode: use `SET client_min_messages = WARNING;` instead of NOTICE to hide verbose messages within psql as well

lib/sh/db.sh: psql(): replaced `test "$verbose_ok" && can_log` with bool var $verbose_

fix: lib/sh/db.sh: psql(): $verbose_: renamed to $verbose_ok for clarity

fix: lib/sh/util.sh: stdout_contains(): add another pipe_delay because the `grep` statement was sometimes getting printed before its filtered output

bugfix: schemas/util.sql: set_col_types(): need to COALESCE the executed SQL to '' because util.eval() does not support NULL (and shouldn't, because this indicates a missing COALESCE in constructing the statement)

schemas/util.sql: set_col_types(): use simpler util.eval() instead of manual EXECUTE/util.debug_print_sql()

schemas/util.sql: set_col_types(): use string_agg() instead of array_to_string(ARRAY) for clarity

bugfix: lib/sh/util.sh: die_error_hidden(): min verbosity to display error should not be hardcoded

lib/sh/db.sh: psql(): "to see error details" msg: use new die_error_hidden()