HDDS-12058. Use CommandLine out/err in GenericCli subclasses

[adoroszlai]

What changes were proposed in this pull request?

picocli allows setting custom out/err streams to make testing easier. This PR updates subclasses of GenericCli (except OzoneRepair, which is being changed in #7653) to use these custom streams instead of System.out/err. (Further PRs will take care of sets of subcommands to avoid too large patches.)

https://issues.apache.org/jira/browse/HDDS-12058

How was this patch tested?

Tested some of the commands manually:

$ bin/ozone getconf -Dasdf=qwerty confKey asdf
qwerty

$ bin/ozone checknative                       
Native library checking:
hadoop:  false 
ISA-L:   false 
rocks-tools: false 

$ bin/ozone genconf /tmp
ozone-site.xml has been generated at /tmp

CI:
https://github.com/adoroszlai/ozone/actions/runs/12697388661

[nandakumar131]

Thanks @adoroszlai for the improvement. Overall the change looks good to me.
Will it make sense to add helper methods in GenericCli to print the output and error messages? You can ignore this if you feel otherwise.

[adoroszlai]

Will it make sense to add helper methods in GenericCli to print the output and error messages?

Thanks @nandakumar131 for the suggestion. Added out() and err() in GenericCli for easier access to the writers.

[adoroszlai]

Thanks @nandakumar131 for the review.