Track Gravity Forms logging (debug/error) setting changes

[codepuncher]

Fixes #1996.

Adds tracking for Gravity Forms' logging settings to the Gravity Forms connector, following the existing rg_gforms_key pattern (a null entry in $this->options plus a matching check_* method):

• The main "Enable Logging" toggle (gform_enable_logging) is reported as a single enabled/disabled record.
• Each add-on's own logging toggle (gravityformsaddon_gravityformslogging_settings, one entry per plugin slug, e.g. gravityforms for Core or gravityformsstripe for the Stripe add-on) is reported individually when changed on its own.
• Gravity Forms force-enables every add-on's logger as a side effect of the main toggle (enable_all_loggers()). A request-scoped flag skips reporting that cascade separately, so flipping the main toggle produces one record, not one per add-on.
• Deleting the logging option entirely (e.g. uninstalling the Gravity Forms Logging add-on) is reported as a single record, since WordPress's delete_option hook carries no prior value to diff per add-on against.

Checklist

• Project documentation has been updated to reflect the changes in this pull request, if applicable.
• I have tested the changes in the local development environment (see contributing.md).
• I have added phpunit tests.

Release Changelog

• New: Track when Gravity Forms logging (the main toggle and each add-on) is enabled or disabled.