Go: deprecation of io/ioutil

As per the release note of Go 1.16 the use of io/ioutil has been deprecated: https://go.dev/doc/go1.16#ioutil

We have already seen some dependencies move which means that we have a requirement in the e2e test for Go 1.16.

All YuniKorn code should move to the new implementations and move the Go version in the go.mod file to 1.16. The github action etc must also be updated to at least the latest Go 1.16 release (currently go1.16.13) or a go 1.17 release.