Fix filter=count output to avoid empty objects

[dheeraj12347]

Fixes #197 where using filter=count resulted in empty objects being printed in list responses.

Problem

When filter=count is applied, CloudMonkey still iterates over list items and prints empty {} entries.

Fix

• Skip empty rows after filtering
• Omit list fields when no valid entries remain
• Preserve only relevant top-level fields (e.g., "count")

Result

Now the output correctly returns:
{
"count":
}

instead of including empty objects.

Tested locally with CloudMonkey CLI build.