fix(cli): improve validation help message

[jayzhang]

1. fix: https://msazure.visualstudio.com/Microsoft%20Teams%20Extensibility/_workitems/edit/24944869
2. refactor: remove QTreeNode class and related codes
3. move validation codes from api to fx-core

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (dev@e1ef8a0). Click here to learn what that means.
The diff coverage is 90.59%.

Additional details and impacted files

@@          Coverage Diff           @@
##             dev    #9725   +/-   ##
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  Coverage       ?   85.23%           
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  Files          ?      440           
  Lines          ?    24910           
  Branches       ?     4716           
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  Hits           ?    21233           
  Misses         ?     1951           
  Partials       ?     1726           

Files Changed	Coverage Δ
packages/cli/src/utils.ts	93.81% <ø> (ø)
...core/src/component/middleware/actionExecutionMW.ts	69.35% <ø> (ø)
packages/fx-core/src/question/other.ts	81.78% <ø> (ø)
packages/fx-core/src/ui/validationUtils.ts	90.13% <88.88%> (ø)
packages/cli/src/constants.ts	100.00% <100.00%> (ø)
packages/cli/src/questionUtils.ts	72.72% <100.00%> (ø)
packages/fx-core/src/core/FxCore.ts	86.49% <100.00%> (ø)
packages/fx-core/src/index.ts	100.00% <100.00%> (ø)
packages/fx-core/src/ui/visitor.ts	85.02% <100.00%> (ø)
packages/server/src/serverConnection.ts	83.10% <100.00%> (ø)