Feat: add stepGroupName to process.Context

[yangsoon]

Description of your changes

This PR add stepGroupName for process.Context. The sub steps of step-group can use context. stepGroupName to get
the StepGroupName of the step-group.

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

[codecov]

Codecov Report

Patch coverage: 90.74% and project coverage change: -0.60 ⚠️

Comparison is base (c730c05) 67.48% compared to head (329a305) 66.88%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #151      +/-   ##
==========================================
- Coverage   67.48%   66.88%   -0.60%     
==========================================
  Files          49       50       +1     
  Lines        4505     4551      +46     
==========================================
+ Hits         3040     3044       +4     
- Misses       1071     1104      +33     
- Partials      394      403       +9     

Flag	Coverage Δ
e2etests	22.15% <59.25%> (-0.64%)	⬇️
unit-test	64.36% <66.66%> (-0.06%)	⬇️

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

Impacted Files	Coverage Δ
pkg/types/types.go	33.33% <ø> (ø)
pkg/cue/process/datamanager.go	80.00% <80.00%> (ø)
pkg/tasks/custom/task.go	70.45% <90.47%> (+0.83%)	⬆️
pkg/cue/process/handle.go	62.66% <100.00%> (+0.50%)	⬆️
pkg/tasks/builtin/step_group.go	66.94% <100.00%> (+4.81%)	⬆️

... and 6 files with indirect coverage changes

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