Fix(rollout): improve rollback experience

[hongchaodeng]

Introduce canary-rollback step:

steps
- name: rollback
  type: canary-rollback

Users only need to apply this step and it will automatically rollback to the old version from previous rollout:

NAME         READY   UP-TO-DATE   AVAILABLE   AGE
reviews-v1   1/1
reviews-v2   1/1

NAME         READY   UP-TO-DATE   AVAILABLE   AGE
reviews-v1    2/2 
reviews-v2    0/0  

NAME         READY   UP-TO-DATE   AVAILABLE   AGE
reviews-v1   2/2 

[codecov]

Codecov Report

Merging #2294 (d935fc4) into master (8407c0b) will decrease coverage by 0.15%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2294      +/-   ##
==========================================
- Coverage   63.47%   63.31%   -0.16%     
==========================================
  Files         164      164              
  Lines       16426    16426              
==========================================
- Hits        10426    10400      -26     
- Misses       4893     4909      +16     
- Partials     1107     1117      +10     

Flag	Coverage Δ
e2e-rollout-tests	32.71% <ø> (-0.09%)	⬇️
e2etests	38.02% <ø> (-0.22%)	⬇️
unittests	55.81% <ø> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
apis/core.oam.dev/v1beta1/policy_definition.go	0.00% <0.00%> (-50.00%)	⬇️
...erizedworkload/containerizedworkload_controller.go	60.41% <0.00%> (-8.34%)	⬇️
...m.dev/v1alpha1/envbinding/envbinding_controller.go	68.07% <0.00%> (-6.03%)	⬇️
...ponentdefinition/componentdefinition_controller.go	80.00% <0.00%> (-5.56%)	⬇️
...es/policydefinition/policydefinition_controller.go	62.82% <0.00%> (-3.85%)	⬇️
...dev/v1alpha2/application/application_controller.go	75.48% <0.00%> (-3.85%)	⬇️
...g/controller/core.oam.dev/v1alpha2/core/revison.go	71.73% <0.00%> (-2.18%)	⬇️
...ev/v1alpha2/core/scopes/healthscope/healthscope.go	67.42% <0.00%> (-1.31%)	⬇️
...ller/core.oam.dev/v1alpha2/application/revision.go	72.57% <0.00%> (-1.06%)	⬇️
...dev/v1alpha2/applicationconfiguration/component.go	58.26% <0.00%> (-0.79%)	⬇️
... and 5 more

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[wangyikewxgm]

LGTM