* packaging updates
* one package per binary (nimbus_beacon_node, nimbus_validator_client)
* use `-` in package name (`_` is separating the version)
* don't include (un)installation scripts in package
* default metrics port 8108 for vc
* fix several upgrade/install errors in scripts
* add JWT option to service files
* don't attempt to remove user on purge
We're moving from very slow QEMU-virtualised builds to very fast ones
based on cross toolchains.
- refactor jobs; add checksums to release note
- build and publish Docker images with ARM/ARM64 binaries