CQ: Eliminate 'contribution_invoice_settings' 'Setting' in favour of following our standard
When invoicing code was added the setting standard of one setting per key was ignored & several settings (some only relevant when invoicing is enabled), were jumbled into one setting. This is not our standard & there is no intent to change our standard so we need to migrate them into 'real' settings to clean this up. We did 'defered_revenue_enabled' a while back & I just finished it off via https://github.com/civicrm/civicrm-core/pull/16395
I currently have a PR open to migrate out https://github.com/civicrm/civicrm-core/pull/16397 - this includes code to support attempts to get this setting via contribution_invoice_settings for a few releases (in case any extensions are accessing the settings).
I think I need to enhance the spec to handle the show hide thing