refactor the opt

[mouuii]

Description of your changes

Fixes #

I have:

• Read and followed KubeVela's contribution process.
• Related Docs updated properly. In a new feature or configuration option, an update to the documentation is necessary.
• Run make reviewable to ensure this PR is ready for review.
• Added backport release-x.y labels to auto-backport this PR if necessary.

How has this code been tested

Special notes for your reviewer

[FogDong]

Though you want to pass parameters via options, the fields in the StepGeneratorOptions are still exported to users. It seems useless since the options do not limit the usage of the field in the struct.

[mouuii]

Though you want to pass parameters via options, the fields in the StepGeneratorOptions are still exported to users. It seems useless since the options do not limit the usage of the field in the struct.

changed to lower case

[mouuii]

or we can split the types file into multi files