fix: lib/sh/db.sh: pg_table_exists(): use stderr_matches() rather than just the exit status. this also avoids highlighting the benign error.

fix: inputs/input.Makefile: removed no longer used special handling of XML inputs, support for which was never added to the Makefile. (bin/map, however, does support importing an XML file into a database.) this fixes a bug in XAL, which used to abort with an error but now just imports an empty table.

fix: inputs/input.Makefile: %/install: don't ignore errors if table does not exist, to ensure a proper errexit. this is now possible because every dir that this target is being run on should be a data dir. (Source/ used to be a metadata-only dir.)

bugfix: inputs/input.Makefile: $(cleanup): need `set -o pipefail`

inputs/VegBank/run: `rm=1 import()`: updated runtime (1 h)

inputs/VegBank/taxon_observation.**/test.xml.ref: updated inserted row count

inputs/VegBank/projectcontributor_/test.xml.ref: updated inserted row count

bugfix: schemas/util.sql: is_constant(util.col_ref): updated to include standard newline at beginning of comment (applies to newly-imported staging tables)

bugfix: inputs/VegBank/import_order.txt: added missing project, needed to trigger the staging table renaming for the project table

inputs/VegBank/run: documented `rm=1 import()` runtime (>1.5 h)