pgstat: rename some pgstat_send_* functions to pgstat_report_*.
Only the pgstat_send_* functions that are called from outside pgstat*.c are
renamed (the rest will go away). This is done separately from the - quite
large - shared memory statistics patch to make review easier.
Author: Andres Freund <andres@anarazel.de>
Reviewed-By: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Discussion: https://postgr.es/m/
20220404041516.cctrvpadhuriawlq@alap3.anarazel.de