Automatic merge from submit-queue
Separate Direct and Indirect streaming paths, implement indirect path for CRI
This PR refactors the `pkg/kubelet/container.Runtime` interface to remove the `ExecInContainer`, `PortForward` and `AttachContainer` methods. Instead, those methods are part of the `DirectStreamingRuntime` interface which all "legacy" runtimes implement. I also added an `IndirectStreamingRuntime` which handles the redirect path and is implemented by CRI runtimes. To control the size of this PR, I did not fully setup the indirect streaming path for the dockershim, so I left legacy path behind.
Most of this PR is moving & renaming associated with the refactoring. To understand the functional changes, I suggest tracing the code from `getExec` in `pkg/kubelet/server/server.go`, which calls `GetExec` in `pkg/kubelet/kubelet_pods.go` to determine whether to follow the direct or indirect path.
For https://github.com/kubernetes/kubernetes/issues/29579
/cc @kubernetes/sig-node
