feat(kind) let users specify a KIND config file

[rainest]

As seen in Kong/kubernetes-ingress-controller#2258

When creating a KIND cluster, users can specify a KIND configuration file. This requires creating a cluster and then an environment with that existing cluster, since it is not a generic Environment feature.

[shaneutt]

We do need to make sure that we test this locally before merging, then LGTM.

[rainest]

Testing was essentially "it makes the other PR work" and execing into the kubelet to check its kubeadm config did indeed include the change.

A simpler demonstration is to try and load malformed YAML; KIND will quickly complain at you:

11:25:47-0800 esenin $ TEST_KONG_CONTROLLER_IMAGE_LOAD="traines/kic:2.2.0-cert" TEST_KONG_CONTROLLER_IMAGE_OVERRIDE="traines/kic:2.2.0-cert" GOFLAGS="-tags=e2e_tests" dlv test -- -test.v -test.run TestWebhookUpdate
Type 'help' for list of commands.
(dlv) c
=== RUN   TestWebhookUpdate
    features_test.go:107: configuring all-in-one-dbless.yaml manifest test
=== PAUSE TestWebhookUpdate
=== CONT  TestWebhookUpdate
    features_test.go:112: building test cluster and environment
    features_test.go:129: 
        	Error Trace:	features_test.go:129
        	Error:      	Received unexpected error:
        	            	failed to create cluster 1903f8ef-78b7-42cf-9726-eb8a5289fea0: ERROR: failed to create cluster: could not determine kind / apiVersion for config: yaml: line 6: found a tab character where an indentation space is expected
        	            	: exit status 1
        	Test:       	TestWebhookUpdate
--- FAIL: TestWebhookUpdate (0.03s)
FAIL
Process 466676 has exited with status 1

[shaneutt]

Sounds good 🖖 🚢