Add verify-examples.sh and switch from makefiles to go test and go generate

[alexzielenski]

This PR:

• Adds generate.go to deepcopy-gen and defaulter-gen, and fixes the set-gen generate to not rely on GOPATH. This enables the more standard go generate to be used over ad-hoc makefiles
• Adds hack/verify-examples.sh which will be called from CI to:
  1.  Remove generated code
  2. Re-generate code
  3. Run output tests
  4. Check for diff with git
• Changes most example tests to specify the boilerplate header path. Otherwise would rely on having k8s.io/gengo in your GOPATH to run
• Removes all makefiles in favor of go generate and go test workflows

After this PR we will be able to regenerate and rerun all examples tests in CI by invoking hack/verify-examples.sh

/cc @apelisse

[apelisse]

Awesome, can't wait to see the CI!
/lgtm
/approve

[alexzielenski]

/hold

still making this better

[apelisse]

I don't know how I feel about having both the makefile and the shell script?

[alexzielenski]

I don't know how I feel about having both the makefile and the shell script?

agreed. removed the makefiles since they are supplanted by the verify script. However import-boss still retains a makefile since its test is quite different. I could refactor it to run as part of go test but it would have to just be a test that invokes go run of it self

[alexzielenski]

/hold cancel

[apelisse]

/lgtm

[sttts]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: alexzielenski, apelisse, sttts

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