fix(json): Fix JSON items counting function

[niheaven]

Description

Using [System.Linq.Enumerable]::Count() to count JSON objects.

Motivation and Context

• Relates to fix(scoop-virustotal): Adjust json_path parameters to retrieve correct analysis stats #6044
• Relates to fix(json): Don't serialize jsonpath return if only one result #6066
• Relates to fix(scoop-virustotal): continue exec when no app but -a provided #5593
• Relates to fix(json): Serialize jsonpath return #5921

How Has This Been Tested?

Checklist:

• I have read the Contributing Guide.
• I have ensured that I am targeting the develop branch.
• I have updated the documentation accordingly.
• I have updated the tests accordingly.
• I have added an entry in the CHANGELOG.