Notifying users of available add-on updates (#16636)
Closes #15035
Summary of the issue:
Users would like a push notification on NVDA start-up letting them know if add-ons have available updates
Description of user facing changes
When starting NVDA, a dialog will appear notifying users of updatable add-ons if there are available updates.
This will only notify users if the available update is in the same channel as the installed add-on.
There is an "update all" button on the dialog and a list of add-ons with updates available.
There is also an "Open Add-on Store" button to open the add-on store to the updatable add-ons tab.
A setting to disable this. This is a combobox so that in future users can decide between:
notify on updates (default)
automatic update (See Ability to automatically update add-ons #3208)
disabled
Description of development approach
Created a scheduling module to schedule tasks on NVDA start up, using the schedule pip module.
This is so we can have conflict free scheduling. e.g. so NVDA's update notification won't clash with the add-on update notification.
Uses their suggested code to run a background thread for task scheduling: schedule.readthedocs.io/en/stable/background-execution.html
Changed much of the Add-on Store downloading code to be classmethods. This allows us to use it from the message dialog without creating a store instance.
