Retain autorun setup upon updates

[sarathms]

Fix ooni/probe#1464

• Drop using the .first-run file that was being removed during an update causing autorun settings to reset to defaults (disabled)
• Check for autorun files (.plist, .bat, .vbs) upon startup and regenerate them if missing, without changing the autorun status
• Get the autorun status from the scheduler instead of using the settings store

[hellais]

LGTM

[hellais]

@sarathms what's the status of this? Can you look into merging it?

[sarathms]

I rebased this branch with master after the E2E tests were then merged. Turns out the test code has a bug which doesn't handle well cases where the app launches the About window first instead of the main window e.g when there is a auto-update related notice to be shown at launch.

I think we should go ahead and merge this PR because it was already tested manually and no other changes were made during the rebase itself. I will fix the test code separately.