ConnectionString assumes that values are in \w+

canonical.database.postgresql.ConnectionString assumes that values are in \w+, which conveniently truncates production DB hosts (which contain hyphens). The libpq parser conninfo_parse (src/interfaces/libpq/fe-connect.c) places no such restriction, reading up to the next space (ignoring its quote support).

ConnectionString needs to be fixed to use something like [^ ]+. Ideally we'd support quoting too, but that would require a full ugly parser and isn't necessary... we should just restrict escaped or quoted values for now.