audit and cleanup go deps

[lgadban]

• remove solo-kit
• remove skv2
• audit and remove other solo-io utils modules
  • focus on those with a k8s runtime dep?
• remove all the go mod replace

[lgadban]

majority of outlined work handled in #10529

leftover:

• audit and remove other solo-io utils modules
  • focus on those with a k8s runtime dep?

[lgadban]

#10531 handled more, but go-utils is left!

[timflannagan]

There's a bunch of cleanup we can do here:

• Migrate the github.com/avast/retry-go to github.com/avast/retry-go/v4
• Remove github.com/fgrosse/zaptest as there's a single reference in favor of something else that creates a logger
• Consolidate YAML-related dependencies (e.g. github.com/ghodss/yaml, sigs.k8s.io/yaml) if possible
• Consolidate error handling libraries (e.g. github.com/rotisserie/eris and github.com/pkg/errors)
• Determine whether we still need the github.com/saiskee/gettercheck tool
• Removed the github.com/solo-io/go-list-licenses (and it's corresponding package)
• Determine how much github.com/solo-io/go-utils can be ripped out
• Replace github.com/spf13/afero with the stdlib fs.FS (if possible)
• Remove github.com/spf13/pflag in favor of cobra flags. It's just used in docs/
• Remove github.com/stoewer/go-strcase. It's just used in the docs/
• Removed the knative.dev/pkg. There's a minimal number of imports. Manually vendor any of the utilities depending on their LICENSE.

And some open questions:

• Ideally consolidate on ginkgo or github.com/stretchr/testify or stdlib. That's likely too much work to tackle right now
• Do we need go.uber.org/zap given the other github.com/go-logr dependencies?
• Do we need helm.sh/helm/v3 if it's used in install/test and test/. Can we split those into their own modules?