You don't need to run Xcode 10.2 for iOS 12.2 support. You just need access to the appropriate folder in DeviceSupport.
A possible solution is
/Applications
. It's possible to have multiple Xcode versions in the same directory.Create a symbolic link in Terminal.app to have access to the 12.2 device support folder in Xcode 10.2
ln -s /Applications/Xcode102.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/12.2\ \(16E226\) /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport
You can move Xcode 10.2 to somewhere else but then you have to adjust the path.
Now Xcode 10.1 supports devices running iOS 12.2