Crash when parsing custom registry tags

[bnason]

Theila is crashing with a SIGSEGV when navigating to the Overpage page and the Kubernetes cluster is using images with a port. For instance, I'm using a local cache registry and the image for kube-apiserver is registry:5443/k8s.gcr.io/kube-apiserver:v1.22.8. It seems it's trying to parse out v1.22.8 but instead getting 5443/k8s

2022-04-05T14:24:06.725-0500 DEBUG runtime/adapter.go:405 controller starting {"component": "theilaRuntime", "controller": "UpgradeController"}
2022-04-05T14:24:06.726-0500 INFO grpc/grpc.go:124 serve gRPC at 127.0.0.1:45603 {"component": "grpc"}
2022-04-05T14:24:06.726-0500 INFO backend/server.go:104 serving on 127.0.0.1:8080 {"component": "server"}
2022-04-05T14:24:10.531-0500 INFO controllers/upgrade.go:211 reconciled available Kubernetes releases {"component": "theilaRuntime", "controller": "UpgradeController"}
2022-04-05T14:24:15.184-0500 DEBUG ws/subscription.go:105 subscribed {"component": "subscription", "subscription": "f2f9f550-3b15-4566-9676-beaf6c56e1a1", "resource": "TaskStatuses.theila.sidero.dev", "namespace": "", "source": "Theila", "context": "admin@capv-bootstrap"}
2022-04-05T14:24:15.185-0500 DEBUG ws/subscription.go:105 subscribed {"component": "subscription", "subscription": "65bf223e-34d0-44ad-afe7-7332ce30ef4b", "resource": "nodes.v1", "namespace": "", "source": "Kubernetes", "context": "admin@capv-bootstrap"}
2022-04-05T14:24:15.186-0500 DEBUG ws/subscription.go:105 subscribed {"component": "subscription", "subscription": "52f0e435-d518-4b0f-89ad-aeae3060c1a8", "resource": "TaskStatuses.theila.sidero.dev", "namespace": "admin@capv-bootstrap", "source": "Theila", "context": "admin@capv-bootstrap"}
I0405 14:24:16.213955  186061 request.go:665] Waited for 1.035099196s due to client-side throttling, not priority and fairness, request: GET:https://10.5.0.2:6443/apis/flowcontrol.apiserver.k8s.io/v1beta1?timeout=32s
2022-04-05T14:24:22.184-0500 DEBUG ws/subscription.go:105 subscribed {"component": "subscription", "subscription": "e880c850-53e2-400b-a51d-de9f3c147db9", "resource": "pods.v1", "namespace": "", "source": "Kubernetes", "context": "admin@capv-bootstrap"}
2022-04-05T14:24:25.598-0500 DEBUG ws/subscription.go:105 subscribed {"component": "subscription", "subscription": "cea7b951-226f-4fe5-87d7-41a9bf15c7f2", "resource": "TaskStatuses.theila.sidero.dev", "namespace": "", "source": "Theila", "context": "admin@capv-bootstrap"}
2022-04-05T14:24:25.604-0500 DEBUG ws/subscription.go:105 subscribed {"component": "subscription", "subscription": "bce10a71-27e0-4be6-b3d4-fb3e055f5918", "resource": "TaskStatuses.theila.sidero.dev", "namespace": "admin@capv-bootstrap", "source": "Theila", "context": "admin@capv-bootstrap"}
2022-04-05T14:24:27.012-0500 DEBUG ws/subscription.go:105 subscribed {"component": "subscription", "subscription": "2cf606b2-2980-48e5-b957-bd2a60180761", "resource": "TaskStatuses.theila.sidero.dev", "namespace": "", "source": "Theila", "context": "admin@capv-bootstrap"}
2022-04-05T14:24:27.013-0500 DEBUG ws/subscription.go:105 subscribed {"component": "subscription", "subscription": "678bc5c7-275e-4443-8da2-68ae5c7d56e8", "resource": "nodes.v1", "namespace": "", "source": "Kubernetes", "context": "admin@capv-bootstrap"}
2022-04-05T14:24:27.013-0500 DEBUG ws/subscription.go:105 subscribed {"component": "subscription", "subscription": "581d7d5c-3f92-47d0-9861-2316269ceb78", "resource": "pods.v1", "namespace": "", "source": "Kubernetes", "context": "admin@capv-bootstrap"}
2022-04-05T14:24:27.014-0500 DEBUG ws/subscription.go:105 subscribed {"component": "subscription", "subscription": "dd25d54e-818c-4cda-9564-5c7859089114", "resource": "clusters.v1alpha4.cluster.x-k8s.io", "namespace": "", "source": "Kubernetes", "context": "admin@capv-bootstrap"}
failed to parse kube-apiserver container version strconv.ParseInt: parsing "5443/k8s": invalid syntax
failed to parse kube-controller-manager container version strconv.ParseInt: parsing "5443/k8s": invalid syntax
failed to parse kube-proxy container version strconv.ParseInt: parsing "5443/k8s": invalid syntax
failed to parse kube-scheduler container version strconv.ParseInt: parsing "5443/k8s": invalid syntax
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x1bdb8d7]

goroutine 1346 [running]:
github.com/talos-systems/talos/pkg/cluster/kubernetes.DetectLowestVersion({0x2aeb0b0, 0xc000a85e60}, {0x2b15c80, 0xc00009bd80}, {{0x0, 0x0}, {0x0, 0x0}, {0x0, 0x0}, ...})
	/go/pkg/mod/github.com/talos-systems/talos@v1.0.0-beta.1/pkg/cluster/kubernetes/detect.go:67 +0x257
github.com/siderolabs/theila/internal/backend/grpc.(*managementServer).UpgradeInfo(0x1f63e20, {0x2aeb0b0, 0xc000a85e60}, 0xc00087ab68)
	/src/internal/backend/grpc/management.go:57 +0x172
github.com/siderolabs/theila/api/rpc._ManagementService_UpgradeInfo_Handler({0x1f235e0, 0x3ea57e0}, {0x2aeb0b0, 0xc000a85e60}, 0xc0002b87e0, 0x0)
	/src/api/rpc/management_grpc.pb.go:76 +0x170
google.golang.org/grpc.(*Server).processUnaryRPC(0xc00061d340, {0x2b253b0, 0xc0000f8b60}, 0xc000afea20, 0xc0007e7bc0, 0x3e24040, 0x0)
	/go/pkg/mod/google.golang.org/grpc@v1.44.0/server.go:1282 +0xccf
google.golang.org/grpc.(*Server).handleStream(0xc00061d340, {0x2b253b0, 0xc0000f8b60}, 0xc000afea20, 0x0)
	/go/pkg/mod/google.golang.org/grpc@v1.44.0/server.go:1616 +0xa2a
google.golang.org/grpc.(*Server).serveStreams.func1.2()
	/go/pkg/mod/google.golang.org/grpc@v1.44.0/server.go:921 +0x98
created by google.golang.org/grpc.(*Server).serveStreams.func1
	/go/pkg/mod/google.golang.org/grpc@v1.44.0/server.go:919 +0x294