Refactor: tools: Basic cibadmin XML formatted output

Without --show-access --query and without --node-path.

No new behavior yet because --output-as=xml is not yet supported.

For --output-as=xml, this will create a CDATA block in a PCMK_XE_OUTPUT
element.

Ref T116

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>