runtime(pov): deprecate `#render` and `#statistics` in syntax script

runtime(pov): deprecate `#render` and `#statistics` in syntax script

- 3.1g: active
  https://www.povray.org/ftp/pub/povray/Old-Versions/Official-3.1g/Docs/povuser.pdf#page=172
- 3.5 or later: deprecated
  https://www.povray.org/ftp/pub/povray/Old-Versions/Official-3.5/Linux/povlinux.tgz
  ─ povray-3.50c/html/povdoc_172.html
  - https://www.povray.org/documentation/3.7.0/r3_3.html#r3_3_2_7_1

closes: #17177

Signed-off-by: Eisuke Kawashima <e-kwsm@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>