Whenever an API type is not available then both, `flux get all` and
`flux get image all` will just skip over that type instead of logging
an error message.
Before:
```
$ flux get all
✗ failed to get API group resources: unable to retrieve the complete
list of server APIs: source.toolkit.fluxcd.io/v1beta2: the server
could not find the requested resource
[...]
✗ failed to get API group resources: unable to retrieve the complete
list of server APIs: image.toolkit.fluxcd.io/v1beta2: the server could
not find the requested resource
✗ failed to get API group resources: unable to retrieve the complete
list of server APIs: image.toolkit.fluxcd.io/v1beta2: the server could
not find the requested resource
[...]
$ echo $?
0
```
After:
```
$ flux get all
$ echo $?
0
```
closes#3973
Signed-off-by: Max Jonas Werner <mail@makk.es>
173ee5fcdc