Send analytics about automatic updates

[mherrmann]

We are migrating our auto-update implementation on macOS from Sparkle to Omaha 4. We should send some anonymous statistics that allow us to see whether the new implementation is as successful at updating as the previous one. Ideally, we'd get a comparison along the lines of "x% of users who attempted to update from v1.78.102 with Sparkle were able to do so" vs. "y% of users who attempted to update from v1.78.102 with Omaha 4 were able to do so".

[rebron]

cc: @porteron @DJAndries

[mherrmann]

At the moment, it seems that the best solution for this is a metric "Did you update Brave in the last week?" with answers:

1. Yes, with Sparkle.
2. Yes, with Omaha.
3. No, and I'm on Sparkle.
4. No, and I'm on Omaha.