Adds ginkgolinter

[m1kola]

Linter which checks for common ginkgo issues like wrong error assertions (Expect(err).To(BeNil()) instead of Expect(err).NotTo(HaveOccurred())), etc.

It also identifies Expect calls without a matcher. For example, we have 3 such instances in this repo:

test/e2e/rukpakctl_test.go:243:4       ginkgolinter  ginkgo-linter: "Expect": missing assertion method. Expected "Should()", "To()", "ShouldNot()", "ToNot()" or "NotTo()"
internal/storage/storage_test.go:64:3  ginkgolinter  ginkgo-linter: "Expect": missing assertion method. Expected "Should()", "To()", "ShouldNot()", "ToNot()" or "NotTo()"
internal/storage/storage_test.go:69:3  ginkgolinter  ginkgo-linter: "Expect": missing assertion method. Expected "Should()", "To()", "ShouldNot()", "ToNot()" or "NotTo()"

[m1kola]

output (stdout) was empty becasue rukpak logs errors into stderr. So boolean expression was evaluating into false. Since there was no matcher - this was testing nothing.

Good linter 🐶