Test-Json : Add parameter for JSON data file

[GlenAppleton]

Summary of the new feature/enhancement

The Test-Json command already allows for both a file or a string for the schema definition. Please do the same for the actual JSON data being tested. For example:

Test-Json -JsonFile .\MyData.json -SchemaFile .\MySchema.json

Proposed technical implementation details (optional)

This new parameter would be an alternative method to having to load the data in a separate command into a variable using Get-Content -Raw, and it would be consistent with the alternative method already provided for the schema data.