fetch task-queue stats only if available

[kokes]

What was changed

Stats for task-queues are only fetched from a pointer to a struct only if a given pointer is not nil.

Why?

I ran into panics otherwise.

$ temporal task-queue describe -t foo
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x8 pc=0x102d578a0]

goroutine 1 [running]:
github.com/temporalio/cli/temporalcli.buildIDToStatsRows({0x0, 0x0, 0x0}, {0x102dd7920, 0xb}, 0x114180b18?)
	github.com/temporalio/cli/temporalcli/commands.taskqueue.go:158 +0xf0
github.com/temporalio/cli/temporalcli.descriptionToStatsRows({0x14000def320?, 0x0?})
	github.com/temporalio/cli/temporalcli/commands.taskqueue.go:173 +0x74
github.com/temporalio/cli/temporalcli.taskQueueDescriptionToRows({0x14000def320?, 0x0?}, 0xd8?, 0x17?)
	github.com/temporalio/cli/temporalcli/commands.taskqueue.go:202 +0x9c
github.com/temporalio/cli/temporalcli.printTaskQueueDescription(0x14000024a00, {0x14000def320?, 0x0?}, 0x0, 0x0)
	github.com/temporalio/cli/temporalcli/commands.taskqueue.go:220 +0x48
github.com/temporalio/cli/temporalcli.(*TemporalTaskQueueDescribeCommand).run(0x14000c42708, 0x14000024a00, {0x140000dafa0?, 0x0?, 0x0?})
	github.com/temporalio/cli/temporalcli/commands.taskqueue.go:298 +0x330
github.com/temporalio/cli/temporalcli.NewTemporalTaskQueueDescribeCommand.func1(0x14000c42710?, {0x140000dafa0?, 0x4?, 0x102dcaba7?})
	github.com/temporalio/cli/temporalcli/commands.gen.go:2316 +0x38
github.com/spf13/cobra.(*Command).execute(0x14000c42710, {0x140000daf80, 0x2, 0x2})
	github.com/spf13/cobra@v1.9.1/command.go:1019 +0x7bc
github.com/spf13/cobra.(*Command).ExecuteC(0x14000911688)
	github.com/spf13/cobra@v1.9.1/command.go:1148 +0x350
github.com/spf13/cobra.(*Command).Execute(...)
	github.com/spf13/cobra@v1.9.1/command.go:1071
github.com/spf13/cobra.(*Command).ExecuteContext(...)
	github.com/spf13/cobra@v1.9.1/command.go:1064
github.com/temporalio/cli/temporalcli.Execute({0x10b1192d0?, 0x14000220dc0?}, {{0x0, 0x0, 0x0}, {{0x0, 0x0}, {0x0, 0x0}, 0x0}, ...})
	github.com/temporalio/cli/temporalcli/commands.go:350 +0xd0
main.main()
	github.com/temporalio/cli/cmd/temporal/main.go:18 +0x64

Checklist

1. Closes N/A (can create one if needed)

2. How was this tested:

go run ./cmd/temporal task-queue describe -t foo

3. Any docs updates needed?

None

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