docs: add settings editor config-file reference

Document the OpenMV Cam Settings Editor's JSON config format so a user
can author a config from scratch. Convert the settings editor tutorial
page into a directory hub and add a grouped control-type reference:

- index: file anatomy, the keys every control shares, how values are
  saved in place, and a `find(config, *path)` helper for reading values
  back by name (the config is ordered arrays, not a name-keyed dict).
- containers: group and tabs, and the nesting rules.
- value-controls: the seven value controls, the options/values mapping,
  and lineedit input masks / regular expressions.
- display: label.
- example: the full demo config that Create Default Config writes, with
  a name-path read-back.

Everything is harvested from the IDE's settingseditor.cpp (all ten
control types and every JSON key it reads). Also note the settings
editor on the Viewer overview: it stays there in open-only form, so an
operator can change a product's settings without the IDE.

The 26 translation catalogs for the moved page are renamed to follow it;
the new pages are English-only for now and will be translated in a
follow-up.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: kwagyeman