Added Panic Fix on concurrent read and write on map

[anirudhAgniRedhat]

logs show fatal error: concurrent map read and map write

3. oc logs --previous cert-manager-b94b579f-m6j9v -n cert-manager > logs/cert-manager-b94b579f-m6j9v_previous.log
I1206 13:52:20.156106       1 controller.go:251] "cert-manager/controller/build-context: configured acme dns01 nameservers" nameservers=["172.30.0.10:53"]
W1206 13:52:20.156232       1 client_config.go:618] Neither --kubeconfig nor --master was specified.  Using the inClusterConfig.  This might not work.
I1206 13:52:20.157954       1 controller.go:145] "cert-manager/controller: starting leader election"
I1206 13:52:20.157980       1 controller.go:93] "cert-manager/controller: starting metrics server" address="[::]:9402"
I1206 13:52:20.158088       1 controller.go:138] "cert-manager/controller: starting healthz server" address="[::]:9403"
I1206 13:52:20.158571       1 leaderelection.go:250] attempting to acquire leader lease kube-system/cert-manager-controller...
I1206 13:52:20.177614       1 leaderelection.go:260] successfully acquired lease kube-system/cert-manager-controller
I1206 13:52:20.178751       1 controller.go:215] "cert-manager/controller: starting controller" controller="challenges"
I1206 13:52:20.179185       1 controller.go:215] "cert-manager/controller: starting controller" controller="certificaterequests-approver"
I1206 13:52:20.179380       1 controller.go:215] "cert-manager/controller: starting controller" controller="certificaterequests-issuer-ca"
I1206 13:52:20.179636       1 controller.go:215] "cert-manager/controller: starting controller" controller="certificates-metrics"
I1206 13:52:20.179909       1 controller.go:215] "cert-manager/controller: starting controller" controller="certificates-readiness"
I1206 13:52:20.180172       1 controller.go:215] "cert-manager/controller: starting controller" controller="certificates-revision-manager"
I1206 13:52:20.180277       1 controller.go:192] "cert-manager/controller: not starting controller as it's disabled" controller="gateway-shim"
I1206 13:52:20.180389       1 controller.go:215] "cert-manager/controller: starting controller" controller="issuers"
fatal error: concurrent map read and map write

goroutine 91 [running]:
k8s.io/apimachinery/pkg/runtime.(*Scheme).ObjectKinds(0xc0001c59d0, {0x2c883f0?, 0xc000b92140})
	/remote-source/app/cmd/controller/vendor/k8s.io/apimachinery/pkg/runtime/scheme.go:267 +0x1ca
k8s.io/apimachinery/pkg/runtime.WithVersionEncoder.Encode({{0x2c8ed40, 0xc000342540}, {0x2c8a470, 0xc00013ce10}, {0x2c8a3d0, 0xc0001c59d0}}, {0x2c883f0, 0xc000b92140}, {0x2c79640, 0xc000ad16e0})
	/remote-source/app/cmd/controller/vendor/k8s.io/apimachinery/pkg/runtime/helper.go:223 +0x82
k8s.io/apimachinery/pkg/runtime.Encode({0x2c8ecc8, 0xc000ad16b0}, {0x2c883f0, 0xc000b92140})

Added mutex lock to remove concurrent read and writes.

#173

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[sttts]

I think this contradicts the intention of the Scheme type:

Schemes are not expected to change at runtime and are only threadsafe after
// registration is complete.

See above.