[SRU] 2.63

[Ernest Lotter]

This is a new version of snapd.

The changelog is available here https://github.com/snapcore/snapd/blob/2.63/packaging/ubuntu-16.04/changelog, the raw git changelog is available here: https://github.com/snapcore/snapd/commits/2.63 (note that the debian changelog is auto-generated from the merges of the git commits so there is usually no need to look at the raw git commits).

The snappy team released a new release that we want SRU into focal+. The process described in https://wiki.ubuntu.com/SnapdUpdates was used and we have done integration-tests on the snappy images, autopkgtests on classic and unit tests.

GitHub Actions test runs can be found at https://github.com/snapcore/snapd/actions?query=branch%3Arelease%2F2.63