Usernetes

- Dropped support for cgroup v1. Now [cgroup v2](https://rootlesscontaine.rs/getting-started/common/cgroup2/) is an essential requirement. (#237)
- kube-proxy: changed from `userspace` mode to `iptables` mode. Requires [several kernel modules such as `br_netfilter`](https://github.com/rootless-containers/usernetes/blob/v20211108.0/config/modules-load.d/usernetes.conf) to be loaded. (#238)
- Install CoreDNS by default (247)

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Notable changes:
- Remove most of the patches + deprecate "none" cgroup driver (234)

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:warning: The support for cgroup v1 will be removed in the next release. [Upgrading to cgroup v2](https://rootlesscontaine.rs/getting-started/common/cgroup2/) is highly recommended.

Build logs (available for 90 days): https://github.com/rootless-containers/usernetes/runs/3017128248