Refactor internalLabels

[minuk-dev]

related #1411 especially, #1411 (comment), #1411 (review)

Changes

• Simplify withInternalLabels() in cmd/nerdctl/run.go
• Delete setPlatformContainerOptions()

Details

Simplify withInternalLabels() in cmd/nerdctl/run.go

• Problem : As the features of nerdctl expands in the future, the number of internalLabel will continue to increase, but processing by increasing the parameter creates resistance to writing code that increases internalLabel.
• Solution : Abstract and unite internalLabels as a structure.

Delete setPlatformContainerOptions():

• Problem:
  • setPlatformContainerOptions() be created by processing an internalLabel (PIDContainer supporting --pid=container:<name or id>) for linux. But as the structure for internalLabel is created, it is not needed.
  • Due to a structural problem in the code, setPlatformContainerOptions() and setPlatformOptions() query the container twice.
• Solution : Delete setPlatformContainerOptions() and pass a new parameter into setPlatformOptions() for platform specific labels.

[AkihiroSuda]

Thanks