Promote `top` crossplane CLI subcommand to GA

### What problem are you facing?

The `top` subcommand was [introduced](https://github.com/crossplane/crossplane/issues/5036) in crossplane v.1.15 under the _beta_ command.

### How could Crossplane help solve your problem?

In order to promote the `top` command to GA, the following has to be addressed:

```[tasklist]
### Improvements
- [ ] Show crossplane, providers and functions pods custom metrics
- [ ] Make it easier to enable prometheus metrics

```

```[tasklist]
### Fixes
- [ ] Fix the condition where a pod is not yet registered with the metrics server and errors out
```

## Related

- The https://github.com/crossplane/crossplane/issues/4620 will inform what metrics are available.
- https://github.com/crossplane/crossplane/issues/4676