pg_controldata: Show logical decoding status.

pg_controldata: Show logical decoding status.

The logical decoding status is stored in checkpoint records and used
to restore the status at server startup, but pg_controldata did not
show it. This information is useful for diagnosing issues around the
dynamic activation and deactivation of logical decoding.

Oversight in 67c20979ce7.

Reviewed-by: Guoqing Yang <yanggq1988@126.com>
Reviewed-by: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Discussion: https://postgr.es/m/CAD21AoAnPAugUnDic+ESvrfXjXHk2bss9eHAD7zP0-Chy2UabA@mail.gmail.com
Backpatch-through: 19