[Merge] ~juliank/grub/+git/ubuntu:resilient-boot into ~ubuntu-core-dev/grub/+git/ubuntu:ubuntu

[Julian Andres Klode]

FWIW, I followed os-prober's design on where to mount the ESPs and mounted them to /var/lib/grub/esp, os-prober was doing sth similar in /var/lib/os-prober.
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https://code.launchpad.net/~juliank/grub/+git/ubuntu/+merge/381462
Your team Ubuntu Core Development Team is requested to review the proposed merge of ~juliank/grub/+git/ubuntu:resilient-boot into ~ubuntu-core-dev/grub/+git/ubuntu:ubuntu.