WIP enhancement(controller): add type for step spec

[goldenxinxing]

Description

1. add type for step
2. fix enum serialization error

TODO list：

1. add validation in ui
2. add validation in server api

Modules

• UI
• Controller
• Agent
• Client
• Python-SDK
• Others

Checklist

• run code format and lint check
• add unit test
• add necessary doc

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (bca9510) 82.70% compared to head (5f84a58) 73.40%.
Report is 8 commits behind head on main.

Files	Patch %	Lines
...ain/java/ai/starwhale/mlops/api/JobController.java	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #3076      +/-   ##
============================================
- Coverage     82.70%   73.40%   -9.30%     
+ Complexity     3211     3192      -19     
============================================
  Files           571      436     -135     
  Lines         31789    15866   -15923     
  Branches       1873     1873              
============================================
- Hits          26290    11647   -14643     
+ Misses         4677     3393    -1284     
- Partials        822      826       +4     

Flag	Coverage Δ
console	72.09% <ø> (ø)
controller	73.42% <66.66%> (-0.12%)	⬇️
standalone	?
unittests	72.09% <ø> (-19.50%)	⬇️

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[anda-ren]

shall we add plain or customized type for @handler annotation

[anda-ren]

mabe typo for type: StepType