Enhancement: Option to suspend auto update pop-up

End users can accidentally advance their version out in front of local flight tested/validated configurations by clicking on update pop-up (without considering possible side effects). Since there exists a mechanism to update on demand in Help/Check For Updates and Help/Check for Beta Updates buttons, this everyday check and pop-up when there are new versions could be an option in the config.
One option for implementation is to add a check outside of the MainV2.cs background thread update_check logic for a new field defined on the Config/Tuning-Planner page in mission planner (much like check for beta) and store new field in config.xml.

Start by reading the update_check logic in MainV2.cs and the Config/Tuning-Planner page, then trace how settings are stored in config.xml. Confirm how the existing Help/Check For Updates and Help/Check for Beta Updates actions work. Done means an optional setting suppresses the automatic update pop-up while preserving on-demand checks.

Written by the indexing model from the issue text.