Add, build, test and document QEMU ARM support

We would like to have also QEMU ARM support officially in Oniro. The task is to add, build, test and document for 2 machines:

The docs should land similarly as it was done for x86

Edited Aug 16, 2022 by Andrei Gherzan

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information