Edit strict mode to throw errors on additional properties, not found in the schema

[llxp]

This pull request changes the strict mode in such a way, that when there are additional properties in the schema, it throws an error.
It sets additional properties to false in the schema, if strict mode is set.
Also introduces an additional parameter to exclude specific properties using a yaml path.
By default, if no exception is set, the metadata property is excluded, as most k8s yaml schemes are missing it and thus would give out false positives.

[yannh]

Hi @llxp ! Could you expand how this is different from the current behaviour for kubeconform? It should already mark tests as failed when -strict is set and additional properties are found? See this test:

kubeconform/acceptance.bats

Lines 136 to 139 in 808e6d4

	@test "Fail when parsing a config with additional properties and strict set" {
	run bin/kubeconform -strict -kubernetes-version 1.20.0 fixtures/extra_property.yaml
	[ "$status" -eq 1 ]
	}

What exactly are you trying to achieve?