CLI json/yaml output not wrapping single disk(...) by array

[vholer]

Description
As part of implementation in #4950 it was validated, that XSD is respected and entitites, which are expected to appear as multiple instances, must be represented as an array even if there is none or a single one. E.g., DISK, NIC, ...

A manual validation on 6.0.3 / CentOS 8 revels it's not true anymore:

Current output with single disk:

# onevm show 53 --json
...
      "DISK": {
        "ALLOW_ORPHANS": "YES",
        "CLONE": "YES",
...

and with hot-attached second disk:

# onevm show 53 --json
...
      "DISK": [
        {
          "ALLOW_ORPHANS": "YES",
...

**Test must be extended to check these cases!!!**

To Reproduce
CLI show something with --json or --yaml and with single DISK/NIC.

Expected behavior
For none disk, output is like a (or missing)

"DISK": [ ],

For one disk, output is:

"DISK": [ { ... } ],

Details

• Affected Component: CLI
• Version: 6.0.3

Progress Status

• Branch created
• Code committed to development branch
• Testing - QA
• Documentation
• Release notes - resolved issues, compatibility, known issues
• Code committed to upstream release/hotfix branches
• Documentation committed to upstream release/hotfix branches

[xorel]

for 6.0 + master
fix
tests