Typed `Result.Platforms`

[crazy-max]

Instead of a slice of strings in

go-imageinspect/types.go

Line 30 in 0c562e4

Platforms []string

It would be better to have typed platforms []ocispecs.Platform https://github.com/opencontainers/image-spec/blob/2fb996805b3734779bf9a3a84dc9a9691ad7efdd/specs-go/v1/descriptor.go#L52-L72 so we could have OSVersion, OSFeatures.

String representation could then be:

   - linux/ppc64le
   - linux/amd64
   - linux/386
   - linux/s390x
   - linux/riscv64
   - linux/arm64
   - linux/arm/v7
   - linux/arm/v6
   - windows/amd64:10.0.17763.2300
   - windows/amd64:10.0.14393.4770