Update and cleanup to use modern Go language features

[caxu-rh]

It may be easier to review each commit in this PR individually. This PR covers:

• Prefer any instead of interface{} (more readable/intentional)
• Simplify loop syntax and remove unneeded loop-local variables (behavior changed in Go 1.22 to make this unnecessary)
• Use the built-in slices library to remove custom shim types that provide a custom Contains implementation
• Replace usage of io/ioutil package with modern equivalents

[Copilot]

Pull request overview

Modernizes the codebase to use newer Go language/library features and removes legacy shims, improving readability and reducing custom utility code.

Changes:

• Replaces interface{} with any across pullspec, utils, and resolver code paths.
• Adopts standard library helpers (e.g., slices.Contains, slices.Reverse) and Go 1.22+ loop semantics to simplify code.
• Removes io/ioutil usage in favor of os equivalents in tests.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
pkg/pullspec/pullspec.go	Migrates to any, replaces custom slice helpers with slices, and simplifies loop constructs.
pkg/pullspec/heuristic.go	Updates template helper signature and map type to any.
pkg/imageresolver/skopeo.go	Switches JSON map type to any and uses integer range for retry looping.
pkg/imageresolver/script_test.go	Replaces ioutil temp dir + file writes with os equivalents.
internal/utils/vars_test.go	Replaces ioutil temp file + writes with os equivalents.
internal/utils/lens_test.go	Updates test fixtures/expectations to any-typed containers.
internal/utils/lens.go	Migrates to any and simplifies internal slice/function-building logic.
internal/utils/error.go	Updates NewError variadic args to ...any.
cmd/pinning/pinning_test.go	Replaces ioutil calls and updates JSON container types to any.

Comments suppressed due to low confidence (2)

pkg/pullspec/pullspec.go:556

• Log message typo: "relateImage" reads like a misspelling of "relatedImage"/"related image". Consider correcting it to keep logs searchable/consistent.

		log.Printf("%s - Set relateImage %s (from %s): %s\n", csv.path, p.Name(), p.String(), p.Image())
		relatedImages = append(relatedImages, p.AsYamlObject())

cmd/pinning/pinning_test.go:59

• Test setup ignores errors from os.MkdirTemp, os.WriteFile, and imageresolver.GetResolver. These failures can lead to confusing downstream test errors; please check/expect these errors explicitly.

		dir, _ = os.MkdirTemp("", "script")
		manifestDir, _ = os.MkdirTemp("", "pinning_test_")
		csvFilePath = filepath.Join(manifestDir, "clusterserviceversion.yaml")

		resolverScript := filepath.Join(dir, "resolver.sh")

		os.WriteFile(resolverScript, []byte(`#!/bin/bash
if [ "$1" == "registry.example.com/eggs:9.8" ]; then
   echo -n "2"
   exit 0
fi

if [ "$1" == "registry.example.com/maps/spam-operator:1.2" ]; then
   echo -n "1"
   exit 0
fi

exit 1
`), 0700)

		resolver, _ = imageresolver.GetResolver(imageresolver.ResolverScript, map[string]string{
			"path": resolverScript,
		})

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

cmd/pinning/pinning_test.go:55

• The errors from os.MkdirTemp and os.WriteFile are ignored here. In tests, this can hide setup failures and lead to confusing downstream errors; please capture the returned errors and assert success (e.g., with Expect(err).To(Succeed())).

		dir, _ = os.MkdirTemp("", "script")
		manifestDir, _ = os.MkdirTemp("", "pinning_test_")
		csvFilePath = filepath.Join(manifestDir, "clusterserviceversion.yaml")

		resolverScript := filepath.Join(dir, "resolver.sh")

		os.WriteFile(resolverScript, []byte(`#!/bin/bash
if [ "$1" == "registry.example.com/eggs:9.8" ]; then
   echo -n "2"
   exit 0
fi

if [ "$1" == "registry.example.com/maps/spam-operator:1.2" ]; then
   echo -n "1"
   exit 0
fi

exit 1
`), 0700)

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.