chore: speed up resolveResourceReferences

[crenshaw-dev]

Sitting at the airport with nothing better to do than micro-optimize stuff.

before: Benchmark_resolveResourceReferences-16           4676506               252.4 ns/op            82 B/op          3 allocs/op
after: Benchmark_resolveResourceReferences-16            8308146               143.6 ns/op            82 B/op          3 allocs/op

I didn't commit the benchmark code, because it's trivial and shouldn't be needed in the future. Here it is for inspection:

func Benchmark_resolveResourceReferences(b *testing.B) {
	manifest := []byte(`
apiVersion: extensions/v1beta2
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    foo: bar
  uid: '123'
  ownerReferences:
  - apiVersion: apps/v1
    kind: StatefulSet
    name: sw-broker
    uid: '456'
`)
	obj := unstructured.Unstructured{}
	err := yaml.Unmarshal(manifest, &obj.Object)
	require.NoError(b, err)

	c := clusterCache{}

	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		c.resolveResourceReferences(&obj)
	}
}

[crenshaw-dev]

Argo CD tests passed, merging. Thanks, Alex!