Feature: rollout undo command supports fast rollback

[AiRanthem]

$ bin/kubectl-kruise rollout undo rollouts/rollouts-demo -h
Rollback to a previous rollout.

Examples:
  # Rollback to the previous cloneset
  kubectl-kruise rollout undo cloneset/abc
  
  # Rollback to the previous Advanced StatefulSet
  kubectl-kruise rollout undo asts/abc
  
  # Rollback to daemonset revision 3
  kubectl-kruise rollout undo daemonset/abc --to-revision=3
  
  # Rollback to the previous deployment with dry-run
  kubectl-kruise rollout undo --dry-run=server deployment/abc
  
  # Rollback to workload via rollout api object
  kubectl-kruise rollout undo rollout/abc
  
  # Fast rollback during blue-green release (will go back to a previous step with no traffic and most replicas)
  kubectl-kruise rollout undo rollout/abc --fast

Options:
    --allow-missing-template-keys=true:
        If true, ignore any errors in templates when a field or map key is missing in the template. Only applies to
        golang and jsonpath output formats.

    --dry-run='none':
        Must be "none", "server", or "client". If client strategy, only print the object that would be sent, without
        sending it. If server strategy, submit server-side request without persisting the resource.

    --fast=false:
        fast rollback for blue-green release

    -f, --filename=[]:
        Filename, directory, or URL to files identifying the resource to get from a server.

    -k, --kustomize='':
        Process the kustomization directory. This flag can't be used together with -f or -R.

    -o, --output='':
        Output format. One of: (json, yaml, name, go-template, go-template-file, template, templatefile, jsonpath,
        jsonpath-as-json, jsonpath-file).

    -R, --recursive=false:
        Process the directory used in -f, --filename recursively. Useful when you want to manage related manifests
        organized within the same directory.

    --show-managed-fields=false:
        If true, keep the managedFields when printing objects in JSON or YAML format.

    --template='':
        Template string or path to template file to use when -o=go-template, -o=go-template-file. The template format
        is golang templates [http://golang.org/pkg/text/template/#pkg-overview].

    --to-revision=0:
        The revision to rollback to. Default to 0 (last revision).

Usage:
  kubectl-kruise rollout undo (TYPE NAME | TYPE/NAME) [flags] [options]

Use "kubectl-kruise options" for a list of global command-line options (applies to all commands).

[furykerry]

plz also update README to describe the fast rollback option. in addition, try to run the generate-docs command to update the command doc