Improve camera tile add/remove event handling

[jpelgrom]

Summary

Following reports by @dshokouhi in chats and on Discord of camera tiles resetting unexpectedly or not being removed from the app, I tested adding/removing camera tiles again.

For camera tiles resetting, this can be caused by onTileAddEvent or onTileRemoveEvent. This PR updates onTileAddEvent to not overwrite tile data if it already exists, hopefully fixing this (remove+add is annoying, the app would have to add soft delete).

For camera tiles sticking around, during testing I noticed that the system was often destroying the service almost immediately after the add/remove events were sent. As a result, code started in the service's coroutine was cancelled before completing, and a camera tile wasn't added to the database or not removed from the database. I could semi-reliably get it to destroy the service within several milliseconds of adding/removing.

To prevent this, making sure the database work is completed before completing the callback function seems to be the only reliable way (runBlocking). This PR changes it for the camera tiles, during testing it still finishes in <100ms and the app isn't visible at the time (system plays animation) so blocking isn't an issue.

Screenshots

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Link to pull request in Documentation repository

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Any other notes

If accepted I intend to update other tile services to do the same later (there haven't been any complaints yet, but they use other storage which may behave differently on cancellation).

[dshokouhi]

Thanks for the fix 🙏 ! Tough to actually test my issue since theres no direct path to reproduce and it can be days in between but I think the approach is correct and should solve some issues we've seen reported around this.