1.2.1

## Highlights 

⌨️ denotes breaking CLI changes.

👩‍💻 denotes breaking API changes.

- Core
  - [`k8s` plugin for turnkey local Kubernetes cluster](https://github.com/apple/container/issues/2043)
  - [`container export` for live containers](https://github.com/apple/container/issues/1400).
  - [`--ssh` option for `container build`](https://github.com/apple/container/issues/1472).
  - [`--read-only-path` and `--masked-path` for `container run` for Kubernetes, Docker, and similar containers](https://github.com/apple/container/issues/2041).

## What's Changed
* [container]: add `container export` for live containers by @saehejkang in https://github.com/apple/container/pull/1630
* Adjust overcommit and max_map_count vm defaults in guest VMs by @adityabagchi24 in https://github.com/apple/container/pull/2055
* [package]: bump container-builder-shim to 0.13.1 by @saehejkang in https://github.com/apple/container/pull/2056
* [builder]: enable ssh forwarding for container build by @saehejkang in https://github.com/apple/container/pull/1508
* Move SSH builder test to Serialized tests by @JaewonHur in https://github.com/apple/container/pull/2061
* Increase testExecDetachProcessRunning sleep margin to avoid CI flake by @jglogan in https://github.com/apple/container/pull/2063
* Add readiness signal to DirectoryWatcher, fix DirectoryWatcherTest. by @jglogan in https://github.com/apple/container/pull/2066
* Log core counts in CI for perf analysis. by @jglogan in https://github.com/apple/container/pull/2070
* Add `--read-only-path` and `--masked-path` option to container run / create by @adityaramani in https://github.com/apple/container/pull/2069
* Simplify correlation of test prefix to test ID. by @jglogan in https://github.com/apple/container/pull/2071
* Integration test: cache warmup image tarfiles. by @jglogan in https://github.com/apple/container/pull/2074
* K8s plugin by @jshi991 in https://github.com/apple/container/pull/2044

## New Contributors
* @jshi991 made their first contribution in https://github.com/apple/container/pull/2044

**Full Changelog**: https://github.com/apple/container/compare/1.2.0...1.2.1