Add exportId and clientId in the delta data

[suricactus]

This way we can identify deltas on the server side that are comming from the same device and/or the same export. For privacy reasons of our users, we recreate the clientId after each successful export.

The exportId will not be directly used for now, but it is a good statistic for future use.

[qfield-fairy]

🎉 Ta-daaa, freshly created APKs are available for 4cac5a6:

• arm64_v8a

Other architectures: armv7, x86_64, x86